Minimally disruptive retractor and associated methods for spinal surgery

ABSTRACT

This application describes a surgical retractor and related methods for providing access to a surgical target site for the purpose performing minimally invasive spinal fusion across one or more segments of the spinal column.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/791,070, filed Oct. 23, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/756,198, filed Aug. 14, 2015 (now U.S. Pat. No.9,795,370), which claims the benefit of priority under 35 U.S.C. 119(e)from U.S. Provisional Patent Application Ser. No. 62/036,776, filed onAug. 13, 2014, and U.S. Provisional Patent Application Ser. No.62/201,739, filed on Aug. 6, 2015, the entire contents of which are eachhereby expressly incorporated by reference into this disclosure as ifset forth fully herein.

FIELD

This application describes surgical instruments and methods forproviding access to a surgical target site for the purpose performingminimally invasive spinal fusion across one or more segments of thespinal column.

BACKGROUND

Spinal fixation constructs are utilized to provide stability to thespine. Most often the fixation construct is used as an adjunct to fusionsurgery during which adjacent vertebrae are prepared to facilitate bonegrowth between them, thereby eliminating motion between the vertebrae.Because motion between the vertebrae tends to inhibit bone growth, thefixation constructs are employed to prevent motion so that bone can growand achieve a solid fusion. When the position of one or more vertebraemust be adjusted to restore a more natural alignment of the spinalcolumn, the fixation construct also serves to maintain the new alignmentuntil fusion is achieved. Fixation constructs of various forms are wellknown in the art. Most commonly, the fixation construct is a plateanchored to the anterior column with multiple bone anchors or aposterior fixation construct including multiple anchors and a connectingrod anchored to the posterior elements of the spine. For a posteriorfixation construct the anchors (typically pedicle screws) are anchoredinto the pedicles of each vertebra of the target motion segment. Theanchors are then connected by a fixation rod that is locked to eachanchor, thus eliminating motion between the adjacent vertebrae of themotion segment. The posterior fixation construct may be appliedunilaterally or bilaterally. Additionally the posterior fixationconstruct may be applied across multiple levels or motion segments.

The fixation anchors utilized in posterior fixation constructs generallyinclude an anchor portion and a rod housing. The rod housing includes apair of upstanding arms separated by a rod channel in which the fixationrod is captured and locked. When constructing the posterior fixationconstruct the surgeon must align and seat the rod in the rod channel.This can be a challenge, particularly when one or more of the vertebraeto be connected is out of alignment leaving the associated anchor offsetvertically and/or horizontally from the remaining anchor(s) of theconstruct. Constructing the posterior fixation construct under minimallyinvasive access conditions (e.g. minimizing overall incision length andmuscle stripping as compared to traditional open procedures) alsoincreases the difficulty of aligning the rod with the rod channel of theanchor.

The instruments, tools, and techniques described herein are directedtowards reducing these challenges and others associated with posteriorspinal fixation.

SUMMARY

The present application describes a tissue retractor assembly andrelated instruments and methods for performing minimally invasive spinalsurgery, for example transforaminal lumbar interbody fusion (TLIF)surgery. The tissue retractor is used in conjunction with bone anchorsto establish and maintain an operative corridor to the surgical targetsite. More particularly, the retractor anchors to the anatomy (e.g.pedicles) adjacent the surgical target site (e.g. intervertebral disc)to both anchor the exposure and define the boundaries with anatomicallandmarks to orient the surgeon and facilitate navigation. Once thisaccess corridor has been established, the disc space and vertebralendplates may be prepared, one or more interbody implants may beinserted into the disc space, and spinal rods may then be used to alignand compress or reduce the construct.

The retractor assembly includes an access retractor body, first andsecond anchor blades, a secondary retractor, and a secondary blade. Thefirst and second anchor blades capture a portion of bone anchors toanchor the retractor to the anatomy. When fully assembled and inoperation, the access retractor body, anchor blades, and secondary bladeestablish and define a working corridor through which access to thesurgical target site is achieved. This working corridor is expandable ina caudal-cranial direction as well as medially.

The access retractor body includes first and second racks, and left andright arms. The first and second anchor blades are removably attached tothe left and right arms, respectively. In use during a TLIF proceduredescribed herein, the retractor assembly may be positioned relative tothe patient such that the access retractor body is located laterally ofthe wound (away from the patient's body). This advantageously positionsthe main part of the retractor outside of the fluoroscopy window.Although the first anchor blade is described herein as being removablyattached to the left arm and the second anchor blade is described asbeing removably attached to the right arm it should be understood thatthe first and second anchor blades are virtually identical in form andfunction, and therefore are interchangeable.

The access retractor body includes a base having a pair of channelsextending laterally therethrough. The channels are sized and dimensionedto receive the first and second racks therein, and are separated fromone another by a distance sufficient to enable placement of a pinion tocontrol translation of the racks. A thumb tab is rotatable to controlthe directional translation of the racks. By way of example only,rotating the thumb tab in a clockwise direction “opens” the retractor bysimultaneously causing the first rack to translate toward the left(relative to the retractor) and the second rack to translate toward theright. This translation in turn causes the retractor blades to move inthe same direction as the racks, controlling the size of the surgicalwound. Thus, if the access body is positioned laterally of the surgicalwound away from the patient's body, the first retractor blade willtranslate in a caudal direction, and the second retractor blade willtranslate in a cranial direction. A pawl, moveable from a first (e.g.“unlocked”) position to a second (e.g. “locked”) position is provided toenable the user to lock the retractor in an open position during use.The pawl includes a wedge that is configured to engage the teeth of thesecond rack and directly prevent translation of the second rack when thepawl is in the second “locked” position. This also indirectly preventstranslation of the first rack, effectively locking the retractor in an“open” configuration. When the pawl is in the first “unlocked” position,the wedge is disengaged from the teeth, allowing free translation of theracks. A pinion is positioned between the racks and is mechanicallycoupled with the thumb tab such that turning the thumb tab causes thepinion to rotate, which in turn causes the racks to translate. A coiledspring is provided to bias the pawl in a locked position, therebypassively allowing the retractor to open freely. A clip is provided onthe underside of the base and engages a post on the thumb tab to securethe construct together. The access retractor body further includes anarticulating arm attachment to enable attachment to an articulating armto secure the retractor assembly to the patient's bedrail (or otherstatic, rigid mounting location) during use.

By way of example only, the racks are generally rectangular elongatedmembers having a plurality of teeth distributed on one side of each ofthe racks. The teeth are configured to interact with the pinion to allowcontrolled translation of the arms.

The left arm includes a proximal segment and a distal segment. Theproximal segment includes a first aperture and a second aperture. Thefirst aperture is configured to fixedly receive the first rack such thatthe first rack and proximal segment are generally perpendicular to oneanother. Thus, translation of the first rack in either direction causesa corresponding movement of the left arm in the same direction. Thesecond aperture is configured to slidingly receive the second racktherethrough such that the second rack is able to pass through theproximal segment unencumbered in either direction during translation.

The distal segment is connected to the proximal segment and isconfigured to releasably engage the first anchor blade. The distalsegment includes a generally cylindrical housing having a distal face.The distal face includes a central post protruding distally from thecenter of the distal face and a pair of opposing recesses positioned onthe perimeter of the distal face on either side of the central post. Thecentral post is configured to mate with the attachment aperture of theanchor blade to securely attach the anchor blade to the left arm. Thecentral post is generally cylindrical and includes a tapered leading endand a circumferential recess positioned between the leading end and thedistal face. The housing is able to rotate, thus causing the anchorblade to rotate and effect tissue distraction. This rotation isindependent of the second anchor blade, and controlled by a splay unit.The splay unit includes a flange extending laterally away from thehousing, a threaded jack screw, and a cap. The jack screw is pivotablysecured to the flange via a post. The cap includes a threaded centralaperture and an engagement recess for receiving a distal end of anactivation instrument (not shown) such as a T-handle (for example). Asthe cap is rotated by the activation instrument, it translates (ineither direction depending on the direction of rotation of theinstrument) along the jack screw. This causes the jack screw to pivotabout the pin, which in turn causes the cap to transfer a torque to thehousing, and more specifically the opposing recesses. As describedbelow, the recesses engage with the flanges of the anchor blade, thuscausing the anchor blade to pivot either outward or inward depending onthe rotation of the activation instrument. The splay unit allows forcontinuously variable blade splay and will actuate for example to allowfor −20° to 25° (up to 45° total) of angular splay.

The right arm includes a proximal segment and a distal segment. Theproximal segment includes an aperture configured to fixedly receive thesecond rack such that the second rack and proximal segment are generallyperpendicular to one another. Thus, translation of the second rack ineither direction causes a corresponding movement of the right arm in thesame direction.

The distal segment is connected to the proximal segment and isconfigured to releasably engage the second anchor blade. The distalsegment includes a generally cylindrical housing having a distal face.The distal face includes a central post protruding distally from thecenter of the distal face and a pair of opposing recesses positioned onthe perimeter of the distal face on either side of the central post. Thecentral post is configured to mate with the attachment aperture of theanchor blade to securely attach the anchor blade to the right arm. Thecentral post is generally cylindrical and includes a tapered leading endand a circumferential recess positioned between the leading end and thedistal face. The housing is able to rotate, thus causing the anchorblade to rotate and effect tissue distraction. This rotation isindependent of the first anchor blade, and controlled by a splay unit.The splay unit includes a flange extending laterally away from thehousing, a threaded jack screw, and a cap. The jack screw is pivotablysecured to the flange via a post. The cap includes a threaded centralaperture and an engagement recess for receiving a distal end of anactivation instrument such as a T-handle (for example). As the cap isrotated by the activation instrument, it translates (in either directiondepending on the direction of rotation of the instrument) along the jackscrew. This causes the jack screw to pivot about the pin, which in turncauses the cap to transfer a torque to the housing, and morespecifically the opposing recesses. As described below, the recesses areengaged to the flanges of the anchor blade, thus causing the anchorblade to pivot either outward or inward depending on the rotation of theactivation instrument. The splay unit allows for continuously variableblade splay and will actuate for example to allow for −20° to 25° (up to45° total) of angular splay.

Optionally, the access retractor body may be provided with moveablearms. Providing the retractor with moveable arms may allow for theaccess retractor body to be raised off the patient's skin level to avoidanatomical challenges that might otherwise cause the access retractorbody to dig into the patient's skin, as well as to potentially maneuverthe access retractor body out of the fluoroscopy zone. Each moveable armincludes a middle segment positioned between proximal and distal armsegments such as those described above. For example, the left moveablearm includes a proximal segment, a middle segment, and a distal segment.The right moveable arm includes a proximal segment, a middle segment,and a distal segment. In the interest of expediency, the moveable armfeature will be described in detail with respect to one arm only.However it is to be understood that the moveable arms are virtuallyidentical to one another and thus any feature disclosed may beattributed to either moveable arm.

The proximal segment of the moveable arm includes all of the featurespreviously described in relation to the proximal segment of the left armdescribed above, and further includes a pivot member extending distallyfrom the proximal segment, the pivot member configured to be receivedwithin a proximal recess formed in the proximal end of the middlesegment. The distal segment of the moveable arm includes all thefeatures previously described in relation to the distal segment of theleft arm described above, and further includes a pivot member extendingproximally from the distal segment, the pivot member configured to bereceived within a distal recess formed in the distal end of the middlesegment.

The middle segment is pivotally connected to both the proximal segmentand the distal segment. The middle segment has a proximal end includinga proximal recess configured to receive the pivot member of the proximalsegment. A pin extends through the proximal end and pivot member andprovides an axis about which the middle segment pivots relative to theproximal segment. The middle segment further has a distal end includinga distal recess configured to receive the pivot member of the distalsegment. A pin extends through the distal end and pivot member andprovides an axis about which the distal segment pivots relative to themiddle segment. The middle segment further includes a friction recesspositioned in the middle of the middle segment. The friction recesshouses a friction element comprising a pair of friction pins separatedby a spring. The spring exerts a force equally on the friction pins thatin turn exerts a frictional force on the pivot members. Thus, thefriction element allows movement of the middle segment relative to theproximal and distal segments in the presence of sufficient force toovercome the friction. In the absence of such a force, the frictionelement operates to maintain the position of the middle segment relativeto the proximal segment and distal segments. The double hinge creates aflexible arm construct such that the arms can pivot about and adjust toeliminate caudal-cranial blade skew issues (encountered when facingdifficult patient anatomy).

The first and second anchor blades are virtually identical to each otherin form and function and therefore all features disclosed herein withregard to one anchor blade may be attributable to the other anchor bladeas well. Generally, the anchor blade has a blade portion extending froma coupler. The blade portion has an interior face and an exterior face.The exterior face is generally smooth and rests against the soft tissueduring use. The anchor blade is configured to pivot to effectdistraction as discussed previously. The blade portion has a distal endand a proximal end.

The distal end includes an integral pivot arm such that the distal endis divided into a static arm and a pivot arm. The distal end of thestatic arm includes a static foot extending therefrom and the distal endof the pivot arm includes a pivot foot extending therefrom. Whentogether in a closed position, the pivot foot and static foot act inconcert to form a capture element (e.g. divided ring) having a centeraperture dimensioned to receive a neck of the bone anchor (which alsoincludes a head and a threaded shank). A contact surface on the staticfoot and a contact surface on the pivot foot interface with thegenerally spherical outer surface of the head of the bone anchor to forma polyaxial joint between the bone anchor and anchor blade. The contactsurfaces may each have any shape capable of enabling such a polyaxialrelationship, including but not limited to angled, rounded, and/orspherically concave. The pivot arm is pivotably attached to the distalportion of the anchor blade by a pin that extends through a pivotaperture on the proximal end of the pivot arm and a corresponding pivotaperture on the distal portion of the anchor blade. The pivot armrotates in a plane parallel to the width of the anchor blade such thatthe pivot foot can be separated from the static foot to permit passageof the screw shank, allowing the anchor blade to be disengaged from thebone anchor after tulip coupling. A lateral recess is formed in thepivot foot and is configured to receive a stabilization flange therein.The stabilization flange extends away from the static foot into thelateral recess to ensure the pivot foot remains in the desired plane ofmotion. The static arm includes an inward lateral extension whichinterdigitates with a cutout in the pivot arm which provides additionalstrength to resist a force applied to the ring.

The anchor blade further includes an enclosed channel positioned on oneside of the anchor blade and extending the length of the blade. Alocking shaft extends through the enclosed channel and engages the pivotarm to maintain the pivot foot (and capture element) in a closedposition. This engagement is controlled by an actuator, for example asetscrew, that is engaged by a user to actuate the locking shaft. Thesetscrew includes a threaded body, a distal shelf, and a tool recess.The threaded body is generally cylindrical and configured to engage athreaded recess on the proximal end of the anchor blade. The distalshelf interacts with a proximal tab on the locking shaft in such a waythat when the setscrew is rotated, accordingly the distal shelf exerts adownward force on the proximal tab, causing the locking shaft to advancedistally through the enclosed channel and engage the pivot arm. Acapture ring is provided to prevent the setscrew from backing out of thethreaded recess. The tool recess is configured to receive a distal endof a driver that is used to actuate the setscrew. Although describedherein as a setscrew, the actuator may be any element that a user mayuse to cause movement of the locking shaft, including but not limited toa cam mechanism and the like. The anchor blade further includes a trackthat slidably receives various instruments (e.g. shank/blade inserter,tulip inserter) and light cables.

The coupler is integrally formed with the proximal portion of the anchorblade and provides a spring-loaded quick connect and release mechanismfor engagement with the central post of the left arm (and/or the centralpost of the right arm) described above. It should be understood that theanchor blades are interchangeable in that either anchor blade may beused with either the left arm or right arm. Therefore, only theinteraction between one anchor blade and the left arm is described indetail herein, however all features herein described also apply to theinteraction between the other anchor blade and the right arm. Thecoupler has a proximal half and a distal half. For the purpose of thisdisclosure, the proximal half is defined as the portion of the couplerthat engages with left retractor arm, and the distal half is defined asthe portion of the coupler that engages with the secondary retractor (orthe right retractor arm, if attached thereto). The proximal half anddistal half of the coupler are identical and as such the variousfeatures common to both halves will be assigned the same referencenumerals for clarity.

The coupler includes a housing and a pair of buttons. The housingincludes a proximal face on the proximal end (and an identical distalface on the distal end), an attachment aperture extending through theproximal face, a pair of button apertures, and an interior lumen. Theproximal face includes a pair of flanges extending proximally from theproximal face. When the anchor blade is mated to the left arm, theproximal face flushly interfaces with the distal face of the left arm,and the flanges engage with the recesses formed in the distal face ofthe left arm to enable pivoting of the anchor blade in response to useractivation of the splay unit. The attachment aperture receives thecentral post of the left arm therethrough such that the central post canextend into the interior lumen of the housing. The button apertures areconfigured to allow passage of the buttons into the interior lumen. Thebuttons each have a top surface, a through-hole, a lower ridge, and abottom post. The top surface is generally rounded to maintain a lowprofile and cause minimal disruption to surrounding anatomy during use,and is provided as a user engagement surface. The through-hole receivesthe central post therethrough. The lower ridge is configured to nestwithin the circumferential recess of the central post to prevent egressof the central post during use. The bottom post centers a spring whichbiases the lower ridge into the circumferential recess. During couplingof the anchor blade and the left arm, he tapered leading end of thecentral post enables the central post to overcome the bias and advanceuntil the lower ridge is aligned with the circumferential recess, atwhich point the spring causes the lower ridge to snap intocircumferential recess. To release the blade, the user presses downwardon the top surface, which forces the lower ridge out of thecircumferential recess, enabling removal of the central post. Thebuttons are secured to the coupler via pins that nest in recesses on thebuttons. The coupler may also include alignment markings that act inconcert with alignment markings on the arms to provide visual feedbackto a user that sufficient distraction is achieved.

The anchor blades transmit torque efficiently to the bone anchor (e.g.for compression/distraction) without any loss of polyaxial (tulip)motion. The anchor blades are reusable. The pivot foot of the anchorblade allows for top down loading of large screws where the shank threaddiameter is larger than the diameter of the shank head. The pivot footwill allow a polyaxial tulip to be loaded in top down approach withoutentrapping the anchoring point of the anchor blades.

The secondary (e.g. medial) retractor can attach to an assembledretractor and has a self-locking mechanism. The secondary retractor isattachable to the coupler of the anchor blade and comprises a retractionassembly and a blade assembly. The secondary retractor allows forfurther connection to a secondary (e.g. medial) blade and drives furtheraccess to the spine medially with many degrees of freedom. For example,the secondary retractor may provide for medial retraction, medial splay,caudal-cranial pivoting and caudal-cranial translation. The retractionassembly provides medial retraction and comprises a housing, a threadedshaft, and a perpendicular gear comprising an actuating gear and atranslation gear, rendering fine resolution. The housing has an interiorlumen through which the threaded shaft extends and within which theperpendicular gear is contained. The actuating gear includes a toothportion and an engagement recess. The engagement recess extends throughan aperture formed in the housing and provides an engagement element foran actuator tool. The housing has a circumferential recess configured toaccept a snap ring. The actuating gear is secured to the housing via thesnap ring and a grooved retention washer. The translation gear isoriented perpendicularly relative to the actuating gear. The translationgear includes a tooth portion, a post, and a threaded interior lumen.The tooth portion engages the tooth portion of the actuating gear andcauses rotation of the translation gear when the actuating gear isrotated. The post fits within a retaining ring, which has acircumferential recess configured to receive a snap ring therein. Thesnap ring also fits within groove formed within the interior lumen tosecure the translation gear to the housing. A ball bearing race isprovided to prevent galling between the gears during use.

The threaded shaft mates with the threaded lumen of the translationgear. As the translation gear rotates, the threaded shaft is caused totranslate in either a medial or lateral direction, depending on thedirection of the rotation. The threaded shaft further includes aproximal end that is virtually identical in structure and function tothe distal face of the first arm described above. To wit, the proximalend includes a proximal face, a central post protruding distally fromthe center of the proximal face and a pair of opposing recessespositioned on the perimeter of the proximal face on either side of thecentral post. The central post is configured to mate with the attachmentaperture of the anchor blade (or anchor blade) to securely attach theanchor blade to the left arm. The central post is generally cylindricaland includes a tapered leading end and a circumferential recesspositioned between the leading end and the proximal face. These featuresinteract with the quick release mechanism of the anchor blade describedabove in a manner that is identical to the manner in which thecorresponding structure of the left retractor arm interacts with thequick release mechanism of the anchor blade, and thus a repeatdiscussion is unnecessary. It should be noted, however that in theexample disclosed above in which the anchor blade is attached to theleft retractor arm via the proximal end of the coupler, the secondaryretractor may be contemporaneously attached to the distal end of thecoupler.

The blade assembly extends generally perpendicularly from the retractionassembly and includes a quick release housing and a splay unit. Thequick release housing includes an attachment aperture for receiving theattachment post of the secondary blade and a button that is biased witha spring. The quick release housing is identical to form and function tothe same feature described above in relation to the coupler, and thus adetailed description of the like features need not be repeated.Similarly, the splay unit is identical in form and function to the splayunit of the left arm, and thus a detailed description of the likefeatures need not be repeated. It should be noted however that the splayunit allows for continuously variable blade splay and will actuate forexample to allow for up to 40° of angular splay.

An alternative secondary retractor may be provided that differs from thesecondary retractor described above in that the alternative secondaryretractor attaches to both the left retractor arm (via one anchor blade)and the right retractor arm (via the other anchor blade). Thealternative secondary retractor is attachable to the coupler of thefirst anchor blade and a corresponding coupler of the second anchorblade. The alternative secondary retractor comprises a retractionassembly, a blade assembly, and a second attachment unit. Thealternative secondary retractor allows for further connection to asecondary (e.g. medial) blade and drives further access to the spinemedially with many degrees of freedom. For example, the alternativesecondary retractor may provide for medial retraction, medial splay,caudal-cranial pivoting and caudal-cranial translation. The retractionassembly is identical to the retraction assembly described above. Acrossbar extends generally perpendicularly from the retraction assemblyand terminates at the second attachment unit. The blade assembly ispositioned on the crossbar between the retraction assembly and thesecond attachment unit. The blade assembly includes a quick releasehousing and a splay unit. The quick release housing includes anattachment aperture for receiving the attachment post of the secondaryblade and a button that is biased with a spring. The quick releasehousing is identical in form and function to the same feature describedabove in relation to the coupler, and thus a detailed description of thelike features need not be repeated. Similarly, the splay unit isidentical in form and function to the splay unit of the left arm,including a captured jackscrew and a cap. It should be noted howeverthat the splay unit causes pivoting of the quick release housing (andthus the secondary blade) but does not cause rotation of the crossbar orthe second attachment unit. The splay unit allows for continuouslyvariable blade splay and will actuate for example to allow for up to 40°of angular splay.

The second attachment unit includes a base, an extension, and anattachment post. The attachment post is generally cylindrical andincludes a tapered leading end and a circumferential recess positionedbetween the leading end and the extension. These features interact withthe quick release mechanism of the anchor blade described above in amanner that is identical to the manner in which the correspondingstructure of the left retractor arm interacts with the quick releasemechanism of the anchor blade, and thus a repeat discussion isunnecessary.

The secondary retractor blade includes proximal track portion and adistal blade portion. The proximal track portion has an inner face andan outer face. The inner face includes a recess for nesting with atleast a portion of the distal blade portion. The track portion furtherincludes a track for receiving a light cable (for example) and aplurality of ratchet apertures positioned along the track portionproximally of the recess. The outer face includes an attachment postextending generally perpendicularly away from the outer face. Theattachment post is identical in form and function to the central post ofthe left retractor arm, and interacts with the quick release mechanismof the secondary retractor in the same manner that the central post ofthe left retractor arm interacts with the quick release mechanism of thecoupler. The distal blade portion includes a blade and a guide flange.The blade includes an inner face, an outer face, and a serrated foot atthe distal tip. The inner face may include a slightly concave surface.The serrated foot curves toward the outer surface and helps minimizetissue creep effect. The guide flange engages with the track to couplethe distal blade portion to the proximal track portion. The guide flangefurther includes a cantilever ratcheting mechanism having a proximal endthat interacts with the apertures to maintain a desired length of theblade construct. Guide pins extend through pin apertures in the distalblade portion and into guide tracks to ensure the distal blade portionmaintains proper alignment during use.

To use, the secondary blade may be coupled to a blade inserter. Theblade inserter includes a proximal handle and a distal tip separated byan elongated shaft. The proximal handle includes a release buttonextending proximally therefrom. The distal tip includes side edges thatmate with the track on the proximal track portion to couple thesecondary blade to the blade inserter. The distal tip further includes acantilever ratcheting mechanism having a distal end that interacts withthe apertures to maintain a secure hold on the secondary blade.

To use the secondary blade, first the blade is coupled to the inserteras described above. It should be noted that the distal blade portionshould be initially placed in a fully extended position (i.e. positionedsuch that the distal end of the cantilever ratchet mechanism engages thedistal-most ratchet aperture on the proximal track portion. Thesecondary blade is then manually advanced into the surgical target siteby the user. The distal tip of the blade may be placed first with hapticfeedback in the desired location and then subsequently compressed andconnected to the secondary retractor. Optionally, the user may use thesecondary blade like a Cobb instrument to elevate the tissue at thedistal tip. This simultaneously allows the blade to lengthenappropriately while staying compressively locked. Blade compression isachieved as follows: once the blade engages with an anatomical structure(e.g. soft tissue, bone), the distal end will stop moving. If the usercontinues to apply a downward force on the insertion instrument, thecantilever ratcheting mechanism will cause the distal end to vacate oneratchet aperture for the next proximal ratchet aperture and so on, untilthe desired blade compression is achieved. The user than maneuvers thesecondary blade so that it connects to the secondary retractor via thefeatures described above. If desired, the user may affect blade splaywhile the inserter is still attached, or after it has been disengaged.Further blade compression may occur during blade splay. Once thesecondary blade has been inserted, the release button may be used whichcauses the cantilever ratcheting mechanism to re-engage the ratchetapertures while providing downward force to the distal blade, enablingthe inserter to be removed from the surgical wound whilecontemporaneously allowing the secondary blade to maintain an extendedstate. By way of example, the distal blade portion of the secondaryblade may be made of a titanium material selection that provides forintraoperative fluoroscopy radiolucency.

By way of example, one method of using the tissue retractor assembly ofthe present disclosure is in a TLIF procedure. A beneficial feature ofthe retractor assembly described herein is that the bone anchor may becoupled to the anchor blades prior to introduction into the surgicaltarget site. This is done by first unlocking the pivot foot, insertingthe neck of the bone anchor into the center aperture, and then relockingthe pivot foot as described above. The bone anchor is now coupled to theanchor blade, and now may also be coupled to a driver instrument priorto advancement through the operative corridor. Once the patient has beenproperly positioned, the target area has been identified and exposurehas been established, the bone anchors may be placed in the first targetsites. After tapping the target pedicles, the coupled bone anchor,anchor blade, and inserter may be advanced over the K-wire to the targetsite. The anchor is driven into the bone until either the distal end ofthe driver or the anchor blade bottoms out on bone. The K-wire may beremoved after the threaded shank enters the posterior part of thevertebral body. These steps may be repeated to place a second anchorblade coupled with a bone anchor in a pedicle of an adjacent vertebralbody.

At this point the access retractor body can be attached to the anchorblades on either side (e.g. medial or lateral), however it can beadvantageous to attach the access retractor body to the lateral side ofthe anchor blades (i.e. away from the patient's spine) so to increasevisibility of the target area under fluoroscopy. As described above, theaccess retractor body is connected to the anchor blades by inserting thecentral posts into the quick-connect couplers of the anchor blades. Anaudible click will sound when the access retractor body is properlyengaged to the blades. At this point the retractor assembly may beattached to a articulating arm (for example) using the articulating armattachment. Positioning the retractor assembly so that the anchor bladesare parallel to the disc space ensures the proper medial exposuretrajectory is achieved.

If distraction is desired, the anchor blade may be splayed by using aT-handle (for example) to actuate the cap of the splay unit on the leftretractor arm as described above. Similarly, the anchor blade may beindependently splayed using a T-handle (for example) to actuate the capof the splay unit of the right retractor arm. Rotation of the T-handlesin a clockwise direction causes the blades to splay outward. Since theblades are coupled to the pedicle bones via the bone anchors, this willalso cause distraction of the disc space. The coupler may includealignment markings that act in concert with alignment markings on thearms to provide visual feedback to a user that sufficient distraction isachieved. Once proper alignment has been achieved, the user may rotatethe thumb tab (or for example a T-handle, if desired) in a clockwisedirection to open the retractor and provide soft tissue retraction andinitial visualization of the working corridor.

Once adequate soft tissue retraction as been achieved, asingle-engagement secondary retractor or a dual-engagement secondaryretractor may be added to enable medial retraction. Thesingle-engagement secondary retractor is attached by inserting thecentral post into the distal half of the coupler of the anchor blade. Anaudible click will sound when the secondary retractor has been properlyengaged to the anchor blade. The dual-engagement secondary retractor isattached by inserting the central post into the distal half of thecoupler of the anchor blade, and by inserting the attachment post of thesecond attachment unit into the distal half of the coupler of the anchorblade. Audible clicks will sound when the secondary retractor has beenproperly engaged to each of the anchor blades. A secondary blade is thenselected and attached to an inserter, and then attached to the secondaryretractor. Once the adequate medial blade retraction and splay has beenachieved the release button is pressed on the inserter to release thesecondary blade from the inserter.

From this point the additional steps of the TLIF procedure is carriedout at this level including facetectomy, decompression, furtherdistraction (optionally), disc and endplate preparation, and interbodyimplant insertion. In preparation for rod insertion, a tulip head (notshown) is attached to the bone anchor head while the anchor blades areengaged with the bone anchor at each vertebral level. The rods may alsobe placed and locked down while the anchor blades are attached. Once therod construct is sufficiently in place, the pivot foot is unlocked byrotating the setscrew counterclockwise, which causes the locking shaftto retreat proximally through the enclosed channel and thus disengagethe pivot arm. The pivot arm is allowed to move freely, enabling theanchor blade to be dissociated from the bone anchor and removed from theworking channel. The second anchor blade may be removed from the workingchannel in the same manner as the anchor blade, and the operative woundis closed, completing the procedure.

For multi-level TLIF procedures, the retractor assembly may be used in a“marching technique” to reduce the number of times the pedicles have tobe targeted. For example, for a two-level TLIF (involving three adjacentvertebrae), coupled anchor-blade-inserters are placed in each targetpedicle (i.e. three blades in total at two adjacent levels). Theprocedure is performed as described above with relation to one of thelevels while the third anchor blade is unattached to anything (exceptthe implanted bone anchor). After the TLIF is completed at the firstlevel, the retractor assembly is removed except for the anchor blades.The first anchor blade is left attached to the bone anchor. The middleblade is rotated 180° and then reconnected to the access retractor body(the other retractor arm), along with the third anchor blade. The TLIFis performed at the second level. Once the tulips are down the rod canbe placed connecting all 3 levels and the procedure can then befinished.

An alternative anchor blade configured for use with the tissue retractorassembly described herein is provided. The alternative anchor blade issimilar to the previously described anchor blade except for thequick-connect mechanism. Generally, the present anchor blade has a bladeportion extending from a coupler. The blade portion is identical in formand function to the blade portion of the anchor blade described above,and therefore all features disclosed with respect to blade portion ofthe previously described anchor blade are attributable to blade portionof the presently described anchor blade as well, rendering a repeatdisclosure unnecessary.

The coupler is integrally formed with the proximal portion of the anchorblade and provides an alternative spring-loaded quick connect andrelease mechanism for engagement with the central post of the left arm(and/or the central post of the right arm) described above. It should beunderstood that the present anchor blades and are interchangeable inthat the anchor blade may be used with either the left arm or right arm.Therefore, only the interaction between the anchor blade and the leftarm is described in detail herein, however all features herein describedalso apply to the interaction between the anchor blade and the rightarm. The coupler has a proximal half and a distal half. For the purposeof this disclosure, the proximal half is defined as the portion of thecoupler that engages with left retractor arm, and the distal half isdefined as the portion of the coupler that engages with the secondaryretractor (or the right retractor arm, if attached thereto). Theproximal half and distal half of the coupler are identical.

The coupler includes a housing and a pair of release buttons. Thehousing includes a proximal face on the proximal end (and an identicaldistal face on the distal end), an attachment aperture extending throughthe proximal face, a trigger aperture extending through the proximalface below the attachment aperture, a pair of button recesses, and aninterior lumen. The proximal face includes a pair of flanges extendingproximally from the proximal face. When the anchor blade is mated to theleft arm, the proximal face flushly interfaces with the distal face ofthe left arm, and the flanges engage with the recesses formed in thedistal face of the left arm to enable pivoting of the anchor blade inresponse to user activation of the splay unit. The attachment aperturereceives the central post of the left arm therethrough such that thecentral post can extend into the interior lumen of the housing. Thebutton recesses are configured to provide a low profile nesting locationfor the release buttons when the anchor blade is in a “ready” state(e.g. prior to coupling with a left arm). The button recesses each havea spring recess positioned therein for housing one end of the buttonsprings. The release buttons each have a top surface, a bottom surface,and a locking flange extending from the bottom surface. The top surfaceis generally rounded to maintain a low profile and cause minimaldisruption to surrounding anatomy during use, and is provided as a userengagement surface. The bottom surface includes a spring recess forhousing the other end of the button spring. The locking flange extendsfrom the bottom surface and includes a through-hole and a trigger slotextending below the through-hole. The through-hole receives the centralpost therethrough. The rim of the through-hole is sized and configuredto nest within the circumferential recess of the central post to preventegress of the central post after the central post has been fullyinserted into the lumen (thereby locking the anchor blade to the leftarm). The trigger slot is divided into a first part and a second part.The first part has a width dimension that is complementary to thediameter of the middle portion of the trigger button. The second parthas a width dimension that is complementary to the diameter of the endportion of the trigger button. The coupler further includes aspring-loaded trigger button that is at least partially housed, alongwith a trigger spring, within a trigger lumen positioned underneath theinterior lumen. The trigger button has a base, a middle portion having adiameter that is smaller than the diameter of the base, an end portionhaving a diameter that is smaller than the diameter of the middleportion, and an end cap having a diameter that is greater than thediameter of the end portion.

In a detached or “ready” state (e.g. prior to coupling with the leftarm), the trigger spring exerts an outward force on the base of thetrigger button, which biases the middle portion of the trigger buttonthrough the trigger aperture and at least partially into the first part(i.e. wider part) of the trigger slot. This pulls the release buttondownward so that the release button is nested within the button recessand the button springs are compressed. In this state, the attachmentaperture of the housing is aligned with the through-hole of the releasebutton, thereby allowing the insertion of the central post into theinterior lumen to enable coupling of the anchor blade and the left arm.During coupling of the anchor blade and left arm, as the central post isadvanced through the through-hole and attachment aperture and into theinterior lumen. As this advancement is occurring, the distal face of theleft arm encounters the trigger button and exerts an inward force on theend cap. This inward force is greater than the outward force exerted bythe trigger spring, and the trigger button is urged into the triggerlumen. As the trigger button is pushed further into the trigger lumen,the middle portion is pushed entirely out of the first part of thetrigger slot, leaving only the end portion in the trigger slot. Thebutton spring is thus allowed to release energy by exerting an upwardforce on the bottom surface of the release button. This force snaps therelease button up, causing the end portion of the trigger button to snapinto the second part of the trigger slot while simultaneously causingthe rim of the through-hole to snap into the circumferential recess ofthe central post to prevent egress of the central post after the centralpost has been fully inserted into the lumen (thereby locking the anchorblade to the left arm). The forcible movement of the release buttonmakes the metal-on-metal contact between the rim and the circumferentialrecess audible, providing feedback to the user in the form of an audible“click” to indicate that the anchor blade is secured to the retractorarm. In this “locked” state, the attachment aperture and through-holeare no longer in alignment. To release the anchor blade, the user pushesthe release button. This brings the attachment aperture and through-holeback into alignment while simultaneously evicting the rim from thecircumferential recess, enabling the central post to be removed from thecoupler.

According to another embodiment, a third example of a secondaryretractor that can attach to the tissue retractor assembly is disclosedherein. The third example secondary retractor is attachable to thecoupler of the anchor blade (e.g. any of the anchor blade embodimentsdisclosed herein) and comprises a retraction assembly and a bladeassembly. The present secondary retractor allows for further connectionto a secondary (e.g. medial) blade and drives further access to thespine medially with many degrees of freedom. For example, the presentsecondary retractor may provide for medial retraction, medial splay,caudal-cranial pivoting and caudal-cranial translation. The retractionassembly provides medial retraction and comprises a housing, a rack, agear, and a pawl. The housing has an interior lumen through which therack extends, a gear recess that receives the gear, and a pawl recessthat provides a low profile nest for the pawl. The rack includes aproximal attachment end, a set of top teeth, and a set of side teeth.The attachment end is virtually identical in structure and function tothe distal face of the first arm described above, and thus a repeatdiscussion is unnecessary. The top teeth are spaced relatively closetogether and are configured to engage with the pawl. The side teeth arespaced farther apart than the top teeth and are configured to engage thegear. The larger side teeth allow for greater mechanical advantageduring retraction when engaged with the gear, while the smaller teethallow for more discreet locking positions. The gear includes a toothportion and an engagement recess. The engagement recess receives a postof an actuator element, which also includes an engagement recess forengaging an actuator tool. Rotating the actuator element causes the gearto rotate, which in turn causes the rack to translate within the lumen.The pawl includes a distal engagement tip and a spring-loaded proximalrelease lever. The distal engagement tip engages with the top teeth onthe rack to finely control the locking positions. A spring biases thepawl to contact the rack in a ratchet-like manner. Pushing on therelease lever causes the distal engagement tip to lift off the rack,enabling free movement of the rack. The blade assembly is identical tothe blade assembly described above with reference to first examplesecondary retractor, and thus any feature disclosed in relation to thatblade assembly is applicable to the present blade assembly, rendering arepeat discussion unnecessary.

According to another embodiment, a fourth alternative example of asecondary retractor that can attach to the tissue retractor assembly isdescribed herein. The fourth example secondary retractor is attachableto the caudal anchor blade and comprises a retraction assembly and ablade assembly. The secondary retractor allows for further connection toa secondary (e.g. medial) blade and drives further access to the spinemedially with many degrees of freedom. For example, the secondaryretractor may provide for medial retraction, medial splay,caudal-cranial pivoting and caudal-cranial translation. The retractionassembly provides medial retraction and comprises a housing, a rack, anda gear. The housing has an interior channel through which the rackextends and within which the gear engages the rack. The gear includes atooth portion that engages the rack and an engagement recess thatprovides an engagement element for an actuator tool. The housing furtherhas an attachment flange extending generally downward from the housing,and a pawl configured to engage the teeth of the rack, enabling fineresolution. The attachment flange is sized and configured to slideablyengage the track of the anchor blade. The rack is double sided and has afirst set of teeth positioned on an opposite side of the rack from asecond set of teeth. The first set of teeth are spaced relatively closetogether and are configured to engage with the pawl. The second set ofteeth are spaced farther apart than the first set of teeth and areconfigured to engage the gear. The larger second set of teeth allow forgreater mechanical advantage during retraction when engaged with thegear, while the smaller first set of teeth allow for more discreetlocking positions.

The blade assembly includes a base, pivoting crossbar, a blade couplerand a splay unit. The base is positioned at the distal end of the rackand includes a channel for receiving the pivoting crossbar. The pivotingcrossbar can translate up to an inch in distance and can rotate on axisup to 40° in a continuously variable fashion. The pivoting crossbar mayfreely translate within the channel and has an internal O-ring whichapplies friction during translation guidance. The splay unit controlsrotation and is identical in form and function to the splay unit of theleft arm, and thus a detailed description of the like features need notbe repeated. The pivoting crossbar is attached to a crankshaft that hasan offset knuckle and pivoting stud allowing for attachment of asecondary blade. The crankshaft allows the secondary blade to be splayedoffset of the axis of rotation of the pivoting crossbar. The eccentricmovement persuades a secondary blade to move up and out of the surgeon'sline of sight while splaying. The secondary blade attaches to thesecondary retractor with an internal self-locking quick connectmechanism, for example such as those described above.

The fourth example secondary retractor may be used with a standard rackretractor. The present secondary retractor may also be used with theretractor assembly described above without departing from the scope ofthe disclosure. By way of example only, the standard rack retractor mayinclude a first arm and second arm connected via a crossbar rack. Thefirst and second arms are virtually identical to the left and right armsdescribed above. The crossbar rack is received within a housing, whichitself has a gear and pawl. Anchor blades differ from the severalembodiments described above in that they attach to the bone anchors viahoop shims.

According to one example there is described a posterior spinal retractorfor a maintaining an access corridor to a site along the posteriorspinal column on which a surgical procedure is performed. The surgicalprocedure includes the use of first and second bone anchors anchorableinto a first pedicle of a first vertebra and a second pedicle of asecond vertebra, respectively. The spinal retractor includes a retractorbody, a first blade, and a second blade. The retractor body has a firstarm extending along a first arm axis and a second arm extending along asecond arm axis. The first arm axis and second arm axis are parallel toone another and perpendicular to a first translation axis. The retractorbody is operable to move the first retractor arm and second retractorarm relative to each other in a direction plane parallel to the firsttranslation axis. The first arm includes a splay mechanism operable torotate a portion of the first arm about the first arm axis and thesecond arm includes a splay mechanism operable to rotate a portion ofthe second arm about the second arm axis. The first retractor blade iscoupleable to the first arm and has a distal end and a proximal end. Thedistal end of the first retractor blade includes an integral blade footoperable to directly couple to a first bone anchor shank. The blade footpermits angular adjustability of the first retractor blade relative tothe first bone anchor shank. The second retractor blade is coupleable tothe second arm and has a distal end and a proximal end. The distal endof the second retractor blade includes an integral blade foot operableto directly couple to a second bone anchor shank. The blade footpermitting angular adjustability of the second retractor blade relativeto the second bone anchor shank.

According to another aspect of the posterior spinal retractor the firstretractor blade includes a proximal connector that engages the first armsuch that the rotatable portion of the first arm rotates relative to thefirst retractor blade about a limited first free rotation range. Beyondthe limited first free rotation range the first retractor blade rotateswith rotatable portion of the first arm to splay the distal end of thefirst retractor blade. The second retractor blade also includes aproximal connector that engages the second arm such that the rotatableportion of the second arm rotates relative to the second retractor bladeabout a limited second free rotation range. Beyond the limited secondfree rotation range the second retractor blade rotates with therotatable portion of the second arm to splay the distal end of thesecond retractor blade.

According to another aspect of the posterior spinal retractor theproximal connector of the first retractor blade includes a clutchextension that is received within a clutch cavity on the rotatableportion of the first arm. The clutch extension has a lesser width thanthe width of the clutch cavity and the difference between the clutchextension width and the clutch cavity width defines the limited firstfree rotation range. The clutch becoming engaged when a side wall of theclutch extension contacts a sidewall of the clutch cavity.

According to another aspect of the posterior spinal retractor theproximal connector of the second retractor blade includes a clutchextension that is received within a clutch cavity on the rotatableportion of the second arm. The clutch extension has a lesser width thanthe width of the clutch cavity and the difference between the clutchextension width and the clutch cavity width defines the limited secondfree rotation range. The clutch becoming engaged when a side wall of theclutch extension contacts a sidewall of the clutch cavity.

According to another aspect of the posterior spinal retractor, when thefirst and second retractor blades are coupled to anchored first andsecond bone anchor shanks and the first retractor blade clutch andsecond retractor blade clutch are disengaged, the angle of the operativecorridor between the first and second blades can be adjusted by movingthe retractor body which in turn moves the proximal end of the firstretractor blade and the proximal end of the second retractor blade inthe same direction.

According to another aspect of the posterior spinal retractor, when thefirst and second retractor blades are coupled to anchored first andsecond bone anchor shanks and the first retractor blade clutch andsecond retractor blade clutch are disengaged, the volume of theoperative corridor between the first and second blades can be adjustedby translating the first arm and second arm relative to each other tomove the proximal ends of the first and second blades relative to eachand relative to the anchored distal ends.

According to another aspect of the posterior spinal retractor, when thefirst and second retractor blades are coupled to anchored first andsecond bone anchor shanks and the first retractor blade clutch andsecond retractor blade clutch are engaged, the first and second arms canbe translated relative to each other to adjust the distance between thefirst and second bone anchors.

According to another aspect of the posterior spinal retractor, when thefirst and second retractor blades are coupled to anchored first andsecond bone anchor shanks and the first retractor blade clutch andsecond retractor blade clutch are engaged, at least one of the first andsecond rotatable arm portions can be rotated to adjust the distancebetween the first and second bone anchors to compress or distract thedisc space.

According to another aspect of the posterior spinal retractor theproximal connector of the first retractor blade includes a couplingmechanism configured to automatically lock the first retractor blade tothe first retractor arm upon engagement.

According to another aspect of the posterior spinal retractor thecoupling mechanism includes a release button configured to unlock thefirst retractor blade from the associated retractor body or secondaryretractor body to facilitate decoupling.

According to another aspect of the posterior spinal retractor theproximal connector of the first retractor blade includes a secondcoupling mechanism structurally identical to the first couplingmechanism.

According to another aspect of the posterior spinal retractor, thespinal retractor includes a secondary retractor that couples to thesecond coupling mechanism.

According to another aspect of the posterior spinal retractor the secondretractor blade is structurally identical to the first retractor blade.

According to another aspect of the posterior spinal retractor thesecondary retractor body couples to both the second coupling mechanismof the first retractor blade and the secondary coupling mechanism of thesecond retractor blade.

According to another aspect of the posterior spinal retractor, there isa third retractor blade that is coupleable to the secondary retractorbody.

According to another aspect of the posterior spinal retractor the distalend of the first retractor blade includes a static arm and a pivot armpivotally coupled to the static arm. The blade foot includes a staticfoot extending from the static arm and a pivot foot extending from thepivot foot.

According to another aspect of the posterior spinal retractor the footincludes a center aperture sized to receive a neck of a bone anchortherein.

According to another aspect of the posterior spinal retractor the footincludes an open position with the pivot foot pivoted away from thestatic foot to permit passage of the bone anchor neck into the centeraperture. The foot also includes a closed positon with the pivot footadjacent the static foot to prevent the removal of the bone anchor neckfrom the center aperture.

According to another aspect of the posterior spinal retractor the firstretractor blade further includes a lock to lock the pivot foot in theclosed position.

According to another aspect of the posterior spinal retractor the lockcomprises a shaft that translates through a passage extending along oneside of the retractor blade to engage the pivot arm.

According to another aspect of the posterior spinal retractor the pivotarm is biased to the open position and the shaft engages a rampedsurface of the pivot arm to pivot the pivot arm towards the static armas the shaft translates downward.

According to another aspect of the posterior spinal retractor thetranslation of the shaft is controlled by a set screw situated at thetop of the retractor blade.

According to another aspect of the posterior spinal retractor a gapexists between the ends of the static foot and pivot foot when in theclosed position.

According to another aspect of the posterior spinal retractor an innersurface of the foot is curved and angled.

According to another example, a surgical retractor blade is described.The surgical retractor blade includes a connector and a blade portion.The connector is configured to couple the retractor blade with aretractor. The blade portion includes a distal end having a static armwith a static foot extending transversely from the static arm. Thedistal end also has and a pivot arm with a pivot foot extendingtransversely from the pivot arm. The pivot arm is pivotally coupled tothe static arm and is movable between a closed position and an openposition. In the closed position the pivot foot and static footcooperate to form capture ring. The capture ring is configured tocapture an implantable bone anchor therein. In the open position passageof the implantable bone anchor into and out of the capture ring ispermitted.

According to another aspect of the retractor blade the retractor bladeincludes a lock to lock the pivot arm in the closed position.

According to another aspect of the retractor blade the lock comprises ashaft that translates through a passage extending along one side of theretractor blade to engage the pivot arm.

According to another aspect of the retractor blade the pivot arm isbiased to the open position and the shaft engages a ramped surface ofthe pivot arm to pivot the pivot arm towards the static arm as the shafttranslates downward.

According to another aspect of the retractor blade the translation ofthe shaft is controlled by a set screw situated at the top of theretractor blade.

According to another aspect of the retractor blade a gap exists betweenthe ends of the static foot and pivot foot when in the closed position.

According to another aspect of the retractor blade an inner surface ofthe capture ring is curved and angled.

According to another aspect of the retractor blade the connectorincludes a coupling mechanism configured to automatically lock theretractor blade to the retractor when engaged.

According to another aspect of the retractor blade the couplingmechanism includes a release button configured to unlock the retractorblade from the retractor to facilitate decoupling.

According to another aspect of the retractor blade the connectorincludes a second coupling mechanism structurally identical to thecoupling mechanism.

According another example, the present application describes a tissueretractor. The tissue retractor includes first and second elongated rackmembers dimensioned to translate linearly in opposite directions. Eachrack member has a toothed side. The tissue retractor further includes anaccess retractor body. The access retractor body includes a rack housingconfigured to receive the first and second rack members, a pinionpositioned between the first and second rack members and simultaneouslyengaged with the toothed sides of each of the first and second rackmembers, a pawl operable to prohibit translation of the first and secondrack members, and a torque input element in communication with thepinion, the torque input element operable to cause translation of thefirst and second rack members. A first adjustable retractor arm isfixedly attached to the first rack member in a perpendicularorientation, and includes a proximal segment fixedly attached to thefirst rack member and a distal segment coupled to the proximal segment,the distal segment including a blade engagement post and a splayassembly. A second adjustable retractor arm is fixedly attached to thesecond rack member in a perpendicular orientation, and includes aproximal segment fixedly attached to the second rack member and a distalsegment coupled to the proximal segment, the distal segment including ablade engagement post and a splay assembly. The tissue retractor furtherincludes a retractor blade including a coupler and a blade portion, thecoupler being configured to releaseably receive the blade post of thefirst retractor arm, the blade portion extending distally from thecoupler and having a distal end comprising a fixed portion and a pivotportion, the pivot portion being coupled to the fixed portion with a pinsuch that the pivot portion pivots away from the fixed portion in aplane parallel to the width of the blade portion, the pivot portionbeing moveable between a closed, non-pivoted position and an open,pivoted position.

According to another example aspect of the tissue retractor the distalend of the fixed portion of the retractor blade comprises a static foot,the static foot having a first semicircular flange extending away fromthe plane of the width of the blade, the first semicircular flangehaving a first contact surface.

According to another example aspect of the tissue retractor the distalend of the pivot portion comprises a pivot foot having a secondsemicircular flange extending away from the plane of the width of theblade, the second semicircular flange having a second contact surface.

According to another example aspect of the tissue retractor the firstand second semicircular flanges act in concert to form a capture elementhaving a center aperture sized to receive a neck portion of a boneanchor therein when the pivot portion is in the closed position.

According to another example aspect of the tissue retractor the firstand second contact surfaces are sized and dimensioned to receive aportion of a spherical head of a bone anchor therein such that the boneanchor has a polyaxial relationship with the capture element.

According to another example aspect of the tissue retractor theretractor blade includes a locking mechanism for locking the pivotportion in the closed position.

According to another example aspect of the tissue retractor the lockingportion comprises an elongated shaft having a proximal end and a distalend, the proximal end positioned at the proximal end of the retractorblade and the distal end positioned at the distal end of the retractorblade, the elongated shaft being moveable between a locked position inwhich the distal end contacts the pivot portion and an unlocked positionin which the distal end does not contact the pivot portion.

According to another example aspect of the tissue retractor the lockingmechanism includes an actuator positioned at the proximal end of theretractor blade in communication with the elongated shaft such thatrotation of the actuator causes movement of the elongated shaft betweenthe locked and unlocked positions.

According to another example aspect of the tissue retractor, the tissueretractor further includes a second retractor blade having a coupler anda blade portion, the coupler being configured to releaseably receive theblade post of the second retractor arm, the blade portion extendingdistally from the coupler and having a distal end comprising a fixedportion and a pivot portion, the pivot portion being coupled to thefixed portion with a pin such that the pivot portion pivots away fromthe fixed portion in a plane parallel to the width of the blade portion.

According to another example aspect of the tissue retractor the firstand second retractor blades are identical.

According to another example aspect of the tissue retractor, the tissueretractor further comprises a secondary retractor assembly removeablyattached to the coupler, the secondary retractor assembly including athird retractor blade.

According to still another example, a first method, for using a tissueretractor assembly in a transforaminal lumbar interbody fusion (TLIF)surgery is described. The example method includes the steps of: (a)locating a surgical target site in a lumbar spine of a patient; (b)forming an incision to create a surgical wound; (c) attaching a firstretractor blade to a first bone anchor and a first insertion tool, thefirst bone anchor having a spherical head, a threaded shank, and a neckportion positioned between the spherical head and threaded shank; (d)attaching a second retractor blade to a second bone anchor and a secondinsertion tool; (e) advancing the first retractor blade into thesurgical wound while simultaneously implanting the first bone anchorinto a first pedicle; (f) advancing the second retractor blade into thesurgical wound while simultaneously implanting the second bone anchorinto a second pedicle; (g) attaching a tissue retractor to the first andsecond retractor blades, the tissue retractor comprising an accessretractor body, the access retractor body including a rack housingconfigured to receive first and second elongated rack membersdimensioned to translate linearly in opposite directions, each rackmember having a toothed side, a pinion positioned between the first andsecond rack members and simultaneously engaged with the toothed sides ofeach of the first and second rack members, a pawl operable to prohibittranslation of the first and second rack members, and a torque inputelement in communication with the pinion, the torque input elementoperable to cause translation of the first and second rack members, afirst adjustable retractor arm fixedly attached to the first rack memberin a perpendicular orientation, the first retractor arm including aproximal segment fixedly attached to the first rack member and a distalsegment pivotally coupled to the proximal segment, the distal segmentincluding a blade engagement post and a splay assembly, and a secondadjustable retractor arm fixedly attached to the second rack member in aperpendicular orientation, the second retractor arm including a proximalsegment fixedly attached to the second rack member and a distal segmentcoupled to the proximal segment, the distal segment including a bladeengagement post and a splay assembly; and (h) operating the tissueretractor to retract the surgical wound.

According to another example aspect of the first method the firstretractor blade comprises a coupler and a blade portion, the couplerbeing configured to releaseably receive the blade post of the firstretractor arm, the blade portion extending distally from the coupler andhaving a distal end comprising a fixed portion and a pivot portion, thepivot portion being coupled to the fixed portion with a pin such thatthe pivot portion pivots away from the fixed portion in a plane parallelto the width of the blade portion, the pivot portion being moveablebetween a closed, non-pivoted position and an open, pivoted position.

According to another example aspect of the first method the secondretractor blade comprises a coupler and a blade portion, the couplerbeing configured to releaseably receive the blade post of the secondretractor arm, the blade portion extending distally from the coupler andhaving a distal end comprising a fixed portion and a pivot portion, thepivot portion being coupled to the fixed portion with a pin such thatthe pivot portion pivots away from the fixed portion in a plane parallelto the width of the blade portion, the pivot portion being moveablebetween a closed, non-pivoted position and an open, pivoted position.

According to another example aspect of the first method, a further stepof attaching a rod tulip to the spherical head of the bone anchor whilethe bone anchor is attached to the retractor blade is included.

According to another example aspect of the first method, a further stepof securing a spinal rod within the rod tulip is included.

According to another example aspect of the first method a further stepof detaching the retractor blade from the bone anchor after completingthe step of securing a spinal rod within the rod tulip.

According to another example, a second method, for attaching a fixationsystem to the spine of a patient is described. The fixation systemincludes at least two bone anchors and a spinal rod linking the at leasttwo bone anchors. The method includes the steps of: connecting a firstbone anchor to a first retractor blade, advancing the first bone anchorand first retractor blade together to a first spinal vertebra, andanchoring the first bone anchor through a pedicle of the first spinalvertebra; connecting a second bone anchor to a second retractor blade,advancing the second bone anchor and second retractor blade together toa second spinal vertebra, and anchoring the second bone anchor through apedicle of the second vertebra, wherein the second vertebra is separatedfrom the first vertebra by an intervertebral disc space and the firstvertebra, second vertebra, and intervertebral disc space comprise afirst spinal level; connecting the first retractor blade and the secondretractor blade with a retractor body, the retractor body beingpositioned laterally away from the spine relative to the first andsecond retractor blades, operating the retractor body to expand anoperative corridor formed between the first retractor blade and secondretractor blade from the skin level of the patient to the spine; andlinking the first bone anchor and the second bone anchor with the spinalrod.

According to another example aspect of the second method the additionalstep of adjusting the angle of the operative corridor until theoperative corridor is parallel to the intervertebral disc is included.

According to another example aspect of the second method, adjusting theangle of the operative corridor is accomplished by moving a proximal endof the first retractor blade and a proximal end of the second retractorblade in the same direction while a distal end of the first retractorblade remains positioned adjacent the first pedicle and a distal end ofthe second retractor blade remains positioned adjacent the secondpedicle.

According to another example aspect of the second method the angle ofthe operative corridor is adjusted in one of a cephalad or caudaldirection.

According to another example aspect of the second method the angle ofthe operative corridor is adjusted in one of an anterior and posteriordirection.

According to another example aspect of the second method the angle ofthe operative corridor is adjusted in both one of a cephalad and caudaldirection and in one of an anterior and posterior direction.

According to another example aspect of the second method the firstretractor blade is connected to the first bone anchor in a polyaxialengagement and the second retractor blade is connected to the secondbone anchor in a polyaxial engagement.

According to another example aspect of the second method the additionalstep of operating the retractor body to distract the intervertebral discspace is included.

According to another example aspect of the second method the additionalstep of coupling a secondary retractor body directly to one of the firstretractor blade and second retractor blade is included. The secondaryretractor body is positioned medially relative to the first and secondretractor blades. A third retractor blade is connected to the secondaryretractor body.

According to another example aspect of the second method the secondaryretractor body includes a retraction mechanism and splay mechanism.

According to another example aspect of the second method the additionalstep of operating at least one of the secondary retractor bodyretraction mechanism and splay mechanism to expand the size of theoperative corridor medially is included.

According to another example aspect of the second method the secondaryretractor body couples directly to the first retractor blade and thesecond retractor blade.

According to another example aspect of the second method the firstanchor portion is connected to the first retractor blade via a capturering integral to and extending from the a distal end of the firstretractor blade. The capture ring has a center aperture sized to receivea neck of a bone anchor therein.

According to another example aspect of the second method the capturering comprises a static foot and a pivot foot, the pivot foot pivotingaway from the static foot to an open position to permit passage of thebone anchor neck into the capture ring and pivoting towards the staticfoot to a closed position capture the bone anchor neck within thecapture ring center aperture.

According to another example aspect of the second method the firstretractor blade further comprises a lock to lock the pivot foot in theclosed position.

According to another example aspect of the second method the distal endof the first retractor blade includes a static arm and a pivot armpivotally coupled to the static arm, the static foot extending from thestatic arm and the pivot foot extending from the pivot foot.

According to another example aspect of the second method, connecting thethird retractor blade to the secondary retractor body includes advancingthe third retractor blade to the spine while coupled to an insertiontool, using the distal end of the third blade to first elevate tissueoff of the spine and then connecting the third blade to the secondaryretractor body and releasing the insertion tool.

According to another example aspect of the second method the distal endof the third blade includes a distal end extension configured to lock tothe third blade in a number of discrete extension positions, wherein thesteps of using the distal end of the third blade to first elevate tissueoff of the spine and then connecting the third blade to the secondaryretractor body further include the step of manipulating the insertiontool to disengage a lock of the distal extension to adjust the height ofthe blade to connect to the third blade to the secondary retractor bodywhile maintain contact with the spine at the distal end.

According to another example aspect of the second method the additionalstep of operating on the first spinal level through the operatingcorridor prior to linking the first bone anchor and the second boneanchor with the spinal rod is included.

According to another example aspect of the second method operating onthe first spinal level includes one or more of a facetectomy,decompression, annulotomy, and discectomy.

According to another example aspect of the second method at least adiscectomy is performed and comprising the additional step of insertingan implant into the intervertebral space after the discectomy.

According to another example, a third method, for attaching a fixationsystem to the spine of a patient is described. The fixation systemincludes at least two bone anchors and a spinal rod linking the at leasttwo bone anchors. The method includes the steps of: connecting a firstretractor blade directly to a shank of a first bone anchor via a capturemechanism integrally associated with a distal end of the first retractorblade, advancing the first bone ancho shank and first retractor bladetogether to a first spinal vertebra, and anchoring the first bone anchorshank through a pedicle of the first spinal vertebra; connecting asecond retractor blade directly to a shank of a second bone anchor via acapture mechanism integrally associated with a distal end of the secondretractor blade, advancing the second bone anchor shank and secondretractor blade together to a second spinal vertebra, and anchoring thesecond bone anchor shank through a pedicle of the second vertebra,wherein the second vertebra is separated from the first vertebra by anintervertebral disc space and the first vertebra, second vertebra, andintervertebral disc space comprise a first spinal level; connecting aretractor body to the first retractor blade and the second retractorblade and operating the retractor body to expand an operative corridorformed between the first retractor blade and second retractor blade fromthe skin level of the patient to the spine; and linking the first boneanchor and the second bone anchor with a the spinal rod.

According to another example aspect of the third method the additionalstep of adjusting the angle of the operative corridor until theoperative corridor is parallel to the intervertebral disc is included.

According to another example aspect of the third method adjusting theangle of the operative corridor is accomplished by moving a proximal endof the first retractor blade and a proximal end of the second retractorblade in the same direction while a distal end of the first retractorblade remains positioned adjacent the first pedicle and a distal end ofthe second retractor blade remains positioned adjacent the secondpedicle.

According to another example aspect of the third method the angle of theoperative corridor is adjusted in one of a cephalad or caudal direction.

According to another example aspect of the third method the angle of theoperative corridor is adjusted in one of an anterior and posteriordirection.

According to another example aspect of the third method the angle of theoperative corridor is adjusted in both one of a cephalad and caudaldirection and in one of an anterior and posterior direction.

According to another example aspect of the third method the firstretractor blade is connected to the first bone anchor shank in apolyaxial engagement and the second retractor blade is connected to thesecond bone anchor shank in a polyaxial engagement.

According to another example aspect of the third method the additionalstep of operating the retractor body to distract the intervertebral discspace is included.

According to another example aspect of the third method the additionalstep of coupling a secondary retractor body directly to one of the firstretractor blade and second retractor blade, the secondary retractor bodybeing positioned medially relative to the first and second retractorblades, and connecting a third retractor blade to the secondaryretractor body is included.

According to another example aspect of the third method the secondaryretractor body includes a retraction mechanism and splay mechanism.

According to another example aspect of the third method the additionalstep of operating at least one of the secondary retractor bodyretraction mechanism and splay mechanism to expand the size of theoperative corridor medially is included.

According to another example aspect of the third method the secondaryretractor body couples directly to the first retractor blade and thesecond retractor blade.

According to another example aspect of the third method the first anchorportion is connected to the first retractor blade via a capture ringintegral to and extending from the a distal end of the first retractorblade, the capture ring capture ring having a center aperture sized toreceive a neck of a bone anchor therein.

According to another example aspect of the third method the capture ringcomprises a static foot and a pivot foot, the pivot foot pivoting awayfrom the static foot to an open position to permit passage of the boneanchor neck into the capture ring and pivoting towards the static footto a closed position capture the bone anchor neck within the capturering center aperture.

According to another example aspect of the third method the firstretractor blade further comprises a lock to lock the pivot foot in theclosed position.

According to another example aspect of the third method the distal endof the first retractor blade includes a static arm and a pivot armpivotally coupled to the static arm, the static foot extending from thestatic arm and the pivot foot extending from the pivot foot.

According to another example aspect of the third method connecting thethird retractor blade to the secondary retractor body includes advancingthe third retractor blade to the spine while coupled to an insertiontool, using the distal end of the third blade to first elevate tissueoff of the spine and then connecting the third blade to the secondaryretractor body and releasing the insertion tool.

According to another example aspect of the third method the distal endof the third blade includes a distal end extension configured to lock tothe third blade in a number of discrete extension positions. The stepsof using the distal end of the third blade to first elevate tissue offof the spine and then connecting the third blade to the secondaryretractor body further include the step of manipulating the insertiontool to disengage a lock of the distal extension to adjust the height ofthe blade to connect to the third blade to the secondary retractor bodywhile maintain contact with the spine at the distal end.

According to yet another example, a fourth method, for fixing a fixationsystem to the spine of a patient is described. The fixation systemincluding at least two bone anchors and a spinal rod linking the atleast two bone anchors, comprising the steps of: connecting a first boneanchor to a first retractor blade, advancing the first bone anchor andfirst retractor blade together to a first spinal vertebra, and anchoringthe first bone anchor through a pedicle of the first spinal vertebra;connecting a second bone anchor to a second retractor blade, advancingthe second bone anchor and second retractor blade together to a secondspinal vertebra, and anchoring the second bone anchor through a pedicleof the second vertebra, wherein the second vertebra is separated fromthe first vertebra by an intervertebral disc space and the firstvertebra, second vertebra, and intervertebral disc space comprise afirst spinal level; connecting a retractor body to the first retractorblade and the second retractor blade and operating the retractor body toexpand an operative corridor formed between the first retractor bladeand second retractor blade cranially and caudally from the skin level ofthe patient to the spine; connecting a secondary retractor body directlyto at least one of the first retractor blade and second retractor blade;connecting a third retractor blade to the secondary retractor body andoperating the secondary retractor body to move the third retractor blademedially and further expand the size of the operative corridor; andlinking the first bone anchor and the second bone anchor with the spinalrod.

According to another example aspect of the fourth method the secondaryretractor body couples directly to the first retractor blade and thesecond retractor blade.

According to another example aspect of the fourth method the secondaryretractor body includes a retraction mechanism and splay mechanism.

According to another example aspect of the fourth method the step ofoperating the secondary retractor body to move the third retractor blademedially includes at least one of operating the retraction mechanism tomove the entire third blade medially and operating the splay mechanismto move the distal end of the third blade medially.

According to another example aspect of the fourth method the firstretractor blade is connected to the first bone anchor shank in apolyaxial engagement and the second retractor blade is connected to thesecond bone anchor shank in a polyaxial engagement.

According to another example aspect of the fourth method the firstanchor portion is connected to the first retractor blade via a capturering integral to and extending from the a distal end of the firstretractor blade, the capture ring capture ring having a center aperturesized to receive a neck of a bone anchor therein.

According to another example aspect of the fourth method the capturering includes a static foot and a pivot foot, the pivot foot pivotingaway from the static foot to an open position to permit passage of thebone anchor neck into the capture ring and pivoting towards the staticfoot to a closed position capture the bone anchor neck within thecapture ring center aperture.

According to another example aspect of the fourth method the firstretractor blade further includes a lock to lock the pivot foot in theclosed position.

According to another example aspect of the fourth method the distal endof the first retractor blade includes a static arm and a pivot armpivotally coupled to the static arm, the static foot extending from thestatic arm and the pivot foot extending from the pivot foot.

According to another example aspect of the fourth method connecting thethird retractor blade to the secondary retractor body includes advancingthe third retractor blade to the spine while coupled to an insertiontool, using the distal end of the third blade to first elevate tissueoff of the spine and then connecting the third blade to the secondaryretractor body and releasing the insertion tool.

According to another example, a fifth method, for performing a spinalfusion procedure on a spinal segment of a human spine, the spinalsegment including at least a first vertebra and a second vertebraseparated from the first vertebra by an intervertebral disc space isdescribed. The method includes the steps of: (a) anchoring a firstanchor portion to a first pedicle, the first anchor portion beingdirectly connected to a first retractor blade of a retractor assemblyvia a mechanism integrally associated with a distal end of the firstretractor blade; (b) anchoring a second anchor portion to a secondpedicle, the second anchor portion being directly connected to a secondretractor blade of the retractor assembly via a mechanism integrallyassociated with a distal end of the second retractor blade; (c)connecting the first retractor blade to a first arm of a retractor bodyof the retractor assembly and connecting the second retractor blade to asecond arm of the retractor body; (d) operating the retractor body toincrease the distance between the first arm and the second arm to expandan operating corridor between the first retractor blade and the secondretractor blade; (e) connecting a secondary retractor body directly toat least one of the first retractor blade and second retractor blade,(f) advancing a third retractor blade through the operative corridor andconnecting the third retractor blade to the secondary retractor body,and operating the secondary retractor body to move the third retractorblade and further expand the size of the operating corridor; (f)preparing the intervertebral disc space to receive an implant; (g)implanting a fusion implant in the intervertebral disc space; (h)disconnecting the first retractor blade from the first anchor portionand attaching a first receiver portion to the first anchor portion; (i)disconnecting the second retractor blade from the second retractorportion and attaching a second receiver portion to the second anchorportion; (j) inserting and locking a rod into the first receiver portionand second receiver portion; and (k) removing the first and secondretractor blades from the operative corridor and closing the operativecorridor.

According to another example aspect of the fifth method the first anchorportion is connected to the first retractor blade via a capture ringintegral to and extending from the a distal end of the first retractorblade.

According to another example aspect of the fifth method the capture ringhas a center aperture sized to receive a neck of a bone anchor therein.

According to another example aspect of the fifth method the capture ringcomprises a static foot and a pivot foot, the pivot foot pivoting awayfrom the static foot to an open position to permit passage of the boneanchor neck into the capture ring and pivoting towards the static footto a closed position capture the bone anchor neck within the capturering center aperture.

According to another example aspect of the fifth method the firstretractor blade further comprises a lock to lock the pivot foot in theclosed position.

According to another example aspect of the fifth method the distal endof the first retractor blade includes a static arm and a pivot armpivotally coupled to the static arm, the static foot extending from thestatic arm and the pivot foot extending from the pivot foot.

According to another example aspect of the fifth method the firstretractor blade includes a proximal connector with dual couplingmechanisms to permit coupling of the first retractor blade to each ofthe retractor body and secondary retractor body.

According to another example aspect of the fifth method the couplingmechanisms are structurally identical to permit each of the retractorbody and the secondary retractor body to couple to either couplingmechanism.

According to another example aspect of the fifth method the dualcoupling mechanisms are configured to automatically lock the firstretractor blade to the associated retractor body or secondary retractorbody upon engagement.

According to another example aspect of the fifth method the dualcoupling mechanisms each include a release button configured to unlockthe first retractor blade from the associated retractor body orsecondary retractor body to facilitate decoupling.

According to another example aspect of the fifth method the secondretractor blade is structurally identical to the first retractor blade.

According to another example aspect of the fifth method the thirdretractor blade has a distal end extension that is configured tosecurely maintain a plurality of discrete extension positions.

According to another example aspect of the fifth method the distal endextension includes a cantilevered ratchet mechanism that engages ratchetgrooves on an inner face of the third retractor blade.

According to another example aspect of the fifth method the distal endextension includes a serrated end curved to maximize contact along alamina.

BRIEF DESCRIPTION OF THE DRAWINGS

Many advantages of the presently described article and related methodswill be apparent to those skilled in the art with a reading of thisspecification in conjunction with the attached drawings, wherein likereference numerals are applied to like elements and wherein:

FIG. 1 is a perspective view of an example of a retractor assemblyaccording to a first embodiment;

FIG. 2 is a top plan view of the retractor assembly of FIG. 1;

FIG. 3 is a side plan view of the retractor assembly of FIG. 1;

FIG. 4 is an exploded perspective view of the retractor assembly of FIG.1;

FIG. 5 is an exploded perspective view of an access retractor bodyforming part of the retractor assembly of FIG. 1;

FIG. 6 is a front plan view of the access retractor body of FIG. 5, withthe splay units in a first position;

FIG. 7 is a sectional view of the access retractor body of FIG. 5;

FIG. 8 is a front plan view of the access retractor body of FIG. 5, withthe splay units in a second position;

FIG. 9 is a perspective view of an alternative example of an accessretractor body forming part of the retractor assembly of FIG. 1according to one embodiment;

FIG. 10 is a sectional view of the access retractor body of FIG. 9;

FIG. 11 is an exploded perspective view of an example of an anchor bladeforming part of the retractor assembly of FIG. 1;

FIG. 12 is a perspective view of the anchor blade of FIG. 11 with thepivot arm in an “unlocked” position;

FIG. 13 is a perspective view of the anchor blade of FIG. 11 juxtaposedwith a setscrew driver instrument configured for use with the anchorblade;

FIG. 14 is a plan view of the anchor blade of FIG. 11 with the pivot armin a “closed” position;

FIG. 15 is a sectional view of the distal portion of the anchor blade ofFIG. 11 with the pivot arm in a “closed” position;

FIG. 16 is a top plan view of the anchor blade of FIG. 11;

FIG. 17 is a sectional view of a portion of the retractor assembly ofFIG. 1;

FIG. 18 is a perspective view of an example of a secondary retractorforming part of the retractor assembly of FIG. 1;

FIG. 19 is an exploded perspective view of the secondary retractor ofFIG. 18;

FIG. 20 is a perspective view of an alternative example of a secondaryretractor forming part of the retractor assembly of FIG. 1;

FIG. 21 is an exploded perspective view of the secondary retractor ofFIG. 20;

FIG. 22 is an exploded view of a secondary retractor blade forming partof the retractor assembly of FIG. 1;

FIG. 23 is a plan view of the back side of the secondary retractor bladeof FIG. 22 juxtaposed with the distal end of an insertion instrumentconfigured for use with the secondary blade;

FIG. 24 is a plan view of the front side of the secondary retractorblade of FIG. 22 juxtaposed with the distal end of an insertioninstrument configured for use with the secondary blade;

FIG. 25 is a plan view of the front side of the secondary retractorblade of FIG. 22 coupled to the distal end of the insertion instrument;

FIG. 26 is a perspective view of the secondary retractor blade of FIG.22 coupled to an insertion instrument;

FIG. 27 is a perspective view of an anchor blade of FIG. 11 coupled to abone anchor, which is coupled to an inserter, comprising one step in anexample method of using the retractor assembly of FIG. 1;

FIG. 28 is a plan view of the anchor blade, bone anchor, and insertercombination of FIG. 27 in use to implant the bone anchor in a vertebra,comprising another step in the example method of using the retractorassembly of FIG. 1;

FIG. 29 is a perspective view of a pair of anchor blades of FIG. 11positioned against adjacent vertebrae, comprising another step in theexample method of using the retractor assembly of FIG. 1;

FIGS. 30-31 are a perspective and top plan views, respectively, of theanchor blades of FIG. 29 with the access retractor body of FIG. 5attached, comprising another step in the example method of using theretractor assembly of FIG. 1;

FIG. 32 is a perspective view of the access retractor body and anchorblade assembly juxtaposed with a secondary retractor of FIG. 18,comprising another step in the example method of using the retractorassembly of FIG. 1;

FIG. 33 is a perspective view of the access retractor body and anchorblade assembly juxtaposed with a secondary retractor of FIG. 20,comprising another step in the example method of using the retractorassembly of FIG. 1;

FIG. 34 is a perspective view of the access retractor body, anchorblade, and secondary retractor assembly juxtaposed with the secondaryblade-inserter combination of FIG. 26, comprising another step in theexample method of using the retractor assembly of FIG. 1;

FIGS. 35-37 are side plan and perspective views of the retractorassembly of FIG. 1 in a final assembled position according to oneexample method;

FIG. 38 is a side plan view of the retractor assembly of FIG. 1 in afinal assembled position with the secondary blade retracted according toone example method;

FIG. 39 is a perspective view of another example of an anchor bladeforming part of the retractor assembly of FIG. 1 according to oneembodiment;

FIG. 40 is an exploded perspective view of the anchor blade of FIG. 39;

FIG. 41 is a sectional view of a portion of the retractor assembly ofFIG. 1 with the anchor blade of FIG. 39 attached;

FIG. 42 is a perspective view of the retractor assembly of FIG. 1 withthe anchor blade of FIG. 39 attached;

FIG. 43 is a perspective view an alternative example of a secondaryretractor forming part of the retractor assembly of FIG. 1;

FIG. 44 is an exploded perspective view of the secondary retractor ofFIG. 43;

FIG. 45 is a perspective view of the retractor assembly of FIG. 1 withthe secondary retractor of FIG. 43 attached;

FIG. 46 is a perspective view an alternative example of a secondaryretractor forming part of the retractor assembly of FIG. 1;

FIG. 47 is an exploded perspective view of the secondary retractor ofFIG. 46; and

FIG. 48 is a perspective view of the secondary retractor of FIG. 46attached to a basic example of a rack retractor.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers'specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The minimally disruptive retractor and related methodsdisclosed herein boast a variety of inventive features and componentsthat warrant patent protection, both individually and in combination.

The present application describes a tissue retractor assembly andrelated instruments and methods for performing minimally invasive spinalsurgery, for example transforaminal lumbar interbody fusion (TLIF)surgery. The tissue retractor is used in conjunction with bone anchorsto establish and maintain an operative corridor to the surgical targetsite. More particularly, the retractor anchors to the anatomy (e.g.pedicles) adjacent the surgical target site (e.g. intervertebral disc)to both anchor the exposure and define the boundaries with anatomicallandmarks to orient the surgeon and facilitate navigation. Once thisaccess corridor has been established, the disc space and vertebralendplates may be prepared, one or more interbody implants may beinserted into the disc space, and spinal rods may then be used to alignand compress or reduce the construct.

Referring to FIGS. 1-4, the retractor assembly 10 includes an accessretractor body 12, first and second anchor blades 14, 16, a secondaryretractor 18, and a secondary blade 20. The first and second anchorblades 14, 16 capture a portion of bone anchors 15 to anchor theretractor 10 to the anatomy. When fully assembled and in operation, theaccess retractor body 12, anchor blades 14, 16, and secondary blade 20establish and define a working corridor 22 through which access to thesurgical target site is achieved. This working corridor 22 is expandablein a caudal-cranial direction as well as medially.

With additional reference to FIG. 5, the access retractor body 12includes first and second racks 24, 26, and left and right arms 28, 30.The first and second anchor blades 14, 16 are removably attached to theleft and right arms 28, 30, respectively. In use during a TLIF proceduredescribed herein, the retractor assembly 10 may be positioned relativeto the patient such that the access retractor body 12 is locatedlaterally of the wound (away from the patient's body). Thisadvantageously positions the main part of the retractor outside of thefluoroscopy window. Although the first anchor blade 14 is describedherein as being removably attached to the left arm 28 and the secondanchor blade 16 is described as being removably attached to the rightarm 30 it should be understood that the first and second anchor blades14, 16 are virtually identical in form and function, and therefore areinterchangeable.

The access retractor body 12 includes a base 32 having first and secondchannels 34, 36 extending laterally therethrough. The first and secondchannels 34, 36 are sized and dimensioned to receive the first andsecond racks 24, 26 respectively therein, and are separated from oneanother by a distance sufficient to enable placement of a pinion 44 tocontrol translation of the racks 24, 26 as described below. A thumb tab38 is rotatable to control the directional translation of the racks 24,26. By way of example only, rotating the thumb tab 38 in a clockwisedirection “opens” the retractor by simultaneously causing the first rack24 to translate toward the left (relative to the retractor) and thesecond rack 26 to translate toward the right. This translation in turncauses the retractor blades 14, 16 to move in the same direction as theracks, controlling the size of the surgical wound. Thus, if the accessbody 12 is positioned laterally of the surgical wound away from thepatient's body, the first retractor blade 14 will translate in a caudaldirection, and the second retractor blade 16 will translate in a cranialdirection. A pawl 40, moveable from a first (e.g. “unlocked”) positionto a second (e.g. “locked”) position is provided to enable the user tolock the retractor 10 in an open position during use. The pawl 40includes a wedge 42 that is configured to engage the teeth 48 of thesecond rack 26 and directly prevent translation of the second rack 26when the pawl 40 is in the second “locked” position. This alsoindirectly prevents translation of the first rack 24, effectivelylocking the retractor 10 in an “open” configuration. When the pawl 40 isin the first “unlocked” position, the wedge 42 is disengaged from theteeth 48, allowing free translation of the racks 24, 26. A pinion 44 ispositioned between the racks 24, 26 and is mechanically coupled with thethumb tab 38 such that turning the thumb tab 38 causes the pinion 44 torotate, which in turn causes the racks 24, 26 to translate. A coiledspring 46 is provided to bias the pawl 40 in a locked position, therebypassively allowing the retractor to open freely. A clip 49 is providedon the underside of the base 32 and engages a post 50 on the thumb tabto secure the construct together. The access retractor body 12 furtherincludes an articulating arm attachment 52 to enable attachment to anarticulating arm 54 to secure the retractor assembly 10 to the patient'sbedrail (or other static, rigid mounting location) during use.

By way of example only, the racks 24, 26 are generally rectangularelongated members having a plurality of teeth 48 distributed on one sideof each of the racks 24, 26. The teeth 48 are configured to interactwith the pinion 44 described above to allow controlled translation ofthe arms 28, 30.

The left arm 28 includes a proximal segment 54 and a distal segment 56.The proximal segment 54 includes a first aperture 58 and a secondaperture 60. The first aperture 58 is configured to fixedly receive thefirst rack 24 such that the first rack 24 and proximal segment 54 aregenerally perpendicular to one another. Thus, translation of the firstrack 24 in either direction causes a corresponding movement of the leftarm 28 in the same direction. The second aperture 60 is configured toslidingly receive the second rack 26 therethrough such that the secondrack 26 is able to pass through the proximal segment 54 unencumbered ineither direction during translation.

The distal segment 56 is connected to the proximal segment 54 and isconfigured to releasably engage the first anchor blade 14. The distalsegment 56 includes a generally cylindrical housing 62 having a distalface 64. The distal face 64 includes a central post 66 protrudingdistally from the center of the distal face 64 and a pair of opposingrecesses 68 positioned on the perimeter of the distal face 64 on eitherside of the central post 66. The central post 66 is configured to matewith the attachment aperture 232 of the anchor blade 14 to securelyattach the anchor blade 14 to the left arm 28. The central post 66 isgenerally cylindrical and includes a tapered leading end 70 and acircumferential recess 72 positioned between the leading end 70 and thedistal face 64. The housing 62 is able to rotate, thus causing theanchor blade 14 to rotate and effect tissue distraction. This rotationis independent of the second anchor blade 16, and controlled by a splayunit 74 (FIGS. 6-8). The splay unit 74 includes a flange 76 extendinglaterally away from the housing 62, a threaded jack screw 78, and a cap80. The jack screw 78 is pivotably secured to the flange 76 via a post82. The cap 80 includes a threaded central aperture 84 and an engagementrecess 86 for receiving a distal end of an activation instrument (notshown) such as a T-handle (for example). As the cap 80 is rotated by theactivation instrument, it translates (in either direction depending onthe direction of rotation of the instrument) along the jack screw 78.This causes the jack screw 78 to pivot about the pin 82, which in turncauses the cap 80 to transfer a torque to the housing 62, and morespecifically the opposing recesses 68. As described below, the recesses68 cooperate with the flanges 236 of the anchor blade 14 and act as aclutch. That is, the recesses 68 (e.g. clutch cavities) receive theflanged 236 (e.g. clutch extensions) when the blade and arm are coupled.The recesses 68 are wider than the flanges 236 such that the flange canrotate within the recess a limited amount until a sidewall of theflanges engages a sidewall of the recess (e.g. the clutch is engaged).Once the clutch is engaged the anchor blade will no longer pivotrelative to the arm and will instead rotate (splay) with the arm, thuscausing the anchor blade 14 to splay either outward or inward dependingon the rotation of the activation instrument. The splay unit 74 allowsfor continuously variable blade splay and will actuate for example toallow for −20° to 25° (up to 45° total) of angular splay. The freedom ofthe anchor blade to pivot relative to the arm initially allows the angleof the blades relative to each other and relative to the spine to beadjusted while the blades are anchored to the bone anchors without, theadjustment acting on the spine itself (e.g. compression or distraction).The clutch also facilitates coupling of the blade to the arm byproviding extra alignment tolerance. Markings aligning with the recess68 sidewall and the flange 236 sidewall may provide visual indication ofthe state of the clutch (i.e. engaged or unengaged).

The right arm 30 includes a proximal segment 88 and a distal segment 90.The proximal segment 88 includes an aperture 92 configured to fixedlyreceive the second rack 26 such that the second rack 26 and proximalsegment 88 are generally perpendicular to one another. Thus, translationof the second rack 26 in either direction causes a correspondingmovement of the right arm 30 in the same direction.

The distal segment 90 is connected to the proximal segment 88 and isconfigured to releasably engage the second anchor blade 16. The distalsegment 90 includes a generally cylindrical housing 94 having a distalface 96. The distal face 96 includes a central post 98 protrudingdistally from the center of the distal face 96 and a pair of opposingrecesses 100 positioned on the perimeter of the distal face 96 on eitherside of the central post 98. The central post 98 is configured to matewith the attachment aperture 232 of the anchor blade 16 to securelyattach the anchor blade 16 to the right arm 30. The central post 98 isgenerally cylindrical and includes a tapered leading end 102 and acircumferential recess 104 positioned between the leading end 102 andthe distal face 96. The housing 94 is able to rotate, thus causing theanchor blade 16 to rotate and effect tissue distraction. This rotationis independent of the first anchor blade 14, and controlled by a splayunit 106 (FIGS. 6-8). The splay unit 106 includes a flange 108 extendinglaterally away from the housing 94, a threaded jack screw 110, and a cap112. The jack screw 110 is pivotably secured to the flange 108 via apost 114. The cap 112 includes a threaded central aperture 116 and anengagement recess 118 for receiving a distal end of an activationinstrument (not shown) such as a T-handle (for example). As the cap 112is rotated by the activation instrument, it translates (in eitherdirection depending on the direction of rotation of the instrument)along the jack screw 110. This causes the jack screw 110 to pivot aboutthe pin 114, which in turn causes the cap 112 to transfer a torque tothe housing 94, and more specifically the opposing recesses 100. Therecesses 100 cooperate with the flanges 236 of the anchor blade 14 andact as a clutch. That is, the recesses 100 (e.g. clutch cavities)receive the flanges 236 (e.g. clutch extensions) when the blade and armare coupled. The recesses 100 are wider than the flanges 236 such thatthe flange can rotate within the recess a limited amount until asidewall of the flanges engages a sidewall of the recess (e.g. theclutch is engaged). Once the clutch is engaged the anchor blade will nolonger pivot relative to the arm and will instead rotate (splay) withthe arm, thus causing the anchor blade 14 to splay either outward orinward depending on the rotation of the activation instrument. The splayunit 74 allows for continuously variable blade splay and will actuatefor example to allow for −20° to 25° (up to 45° total) of angular splay.As described previously, the freedom of the anchor blade to pivotrelative to the arm initially allows the angle of the blades relative toeach other and relative to the spine to be adjusted while the blades areanchored to the bone anchors without, the adjustment acting on the spineitself (e.g. compression or distraction). The clutch also facilitatescoupling of the blade to the arm by providing extra alignment tolerance.Markings aligning with the recess 100 sidewall and the flange 236sidewall may provide visual indication of the state of the clutch (i.e.engaged or unengaged).

Optionally, as depicted in FIGS. 9 and 10, the access retractor body maybe provided with moveable arms 120, 122. Providing the retractor 10 withmoveable arms 120, 122 may allow for the access retractor body 12 to beraised off the patient's skin level to avoid anatomical challenges thatmight otherwise cause the access retractor body 12 to dig into thepatient's skin, as well as to potentially maneuver the access retractorbody 12 out of the fluoroscopy zone. Each moveable arm includes a middlesegment positioned between proximal and distal arm segments such asthose described above. For example, the left moveable arm 120 includes aproximal segment 124, a middle segment 126, and a distal segment 128.The right moveable arm 122 includes a proximal segment 130, a middlesegment 132, and a distal segment 134. In the interest of expediency,the moveable arm feature will be described in detail with respect to onearm only. However it is to be understood that the moveable arms 120, 122are virtually identical to one another and thus any feature disclosedmay be attributed to either moveable arm.

The proximal segment 124 of the moveable arm 120 includes all of thefeatures previously described in relation to the proximal segment 54 ofthe left arm 28 described above, and further includes a pivot member 136extending distally from the proximal segment 124, the pivot member 136configured to be received within a proximal recess 140 formed in theproximal end 138 of the middle segment 126, as described below. Thedistal segment 128 of the moveable arm 120 includes all the featurespreviously described in relation to the distal segment 56 of the leftarm 28 described above, and further includes a pivot member 137extending proximally from the distal segment 128, the pivot member 137configured to be received within a distal recess 146 formed in thedistal end 144 of the middle segment 126, as described below.

The middle segment 126 is pivotally connected to both the proximalsegment 124 and the distal segment 128. The middle segment 126 has aproximal end 138 including a proximal recess 140 configured to receivethe pivot member 136 of the proximal segment 124. A pin 142 extendsthrough the proximal end 138 and pivot member 136 and provides an axisabout which the middle segment 126 pivots relative to the proximalsegment 124. The middle segment further has a distal end 144 including adistal recess 146 configured to receive the pivot member 137 of thedistal segment 128. A pin 148 extends through the distal end 144 andpivot member 137 and provides an axis about which the distal segment 128pivots relative to the middle segment 126. The middle segment 126further includes a friction recess 150 positioned in the middle of themiddle segment 126. The friction recess 150 houses a friction elementcomprising a pair of friction pins 152 separated by a spring 154. Thespring 154 exerts a force equally on the friction pins 152 that in turnexerts a frictional force on the pivot members 136, 137. Thus, thefriction element allows movement of the middle segment 126 relative tothe proximal and distal segments 124, 128 in the presence of sufficientforce to overcome the friction. In the absence of such a force, thefriction element operates to maintain the position of the middle segment126 relative to the proximal segment and distal segments 124, 128. Thedouble hinge creates a flexible arm construct such that the arms canpivot about and adjust to eliminate caudal-cranial blade skew issues(encountered when facing difficult patient anatomy).

FIGS. 11-17 illustrate the anchor blade 14 in greater detail. Anchorblade 16 is virtually identical to anchor blade 14 in form and functionand therefore all features disclosed herein with regard to anchor blade14 may be attributable to anchor blade 16 as well. Generally, anchorblade 14 has a blade portion 156 extending from a coupler 158. The bladeportion 156 has an interior face 160 and an exterior face 162 (FIG. 3).The exterior face 162 is generally smooth and rests against the softtissue during use. The anchor blade 14 is configured to pivot to effectdistraction as discussed previously. The blade portion 156 has a distalend 164 and a proximal end 166.

The distal end 164 includes an integral pivot arm 168 such that thedistal end 164 is divided into a static arm 170 and a pivot arm 168. Thedistal end of the static arm 170 includes a static foot 172 extendingtherefrom and the distal end of the pivot arm 168 includes a pivot foot174 extending therefrom. When together in a closed position (FIG. 16),the pivot foot 174 and static foot 172 act in concert to form a captureelement (e.g. divided ring) having a center aperture 176 dimensioned toreceive a neck 178 of the bone anchor 15 (which also includes a head 180and a threaded shank 182). A contact surface 184 on the static foot 172and a contact surface 186 on the pivot foot 174 interface with thegenerally spherical outer surface of the head 180 of the bone anchor 15to form a polyaxial joint between the bone anchor 15 and anchor blade14. The contact surfaces 184, 186 may each have any shape capable ofenabling such a polyaxial relationship, including but not limited toangled, rounded, and/or spherically concave. A gap may be providedbetween the pivot foot and static foot to reduces the amount the pivotarm is required to pivot in order to permit the anchor shank to escapethe attachment ring. The footprint of the capture ring is also designedto further facilitating separation from the anchor head duringdisengagement. The Inside of the ring is curved and angled in such a wayso that when the locking shaft is released a force applied to the pivotfoot will facilitate the action of opening the pivot foot to permitdisengagement from the anchor. The pivot arm 168 is pivotably attachedto the distal portion 164 of the anchor blade 14 by a pin 190 thatextends through a pivot aperture 192 on the proximal end of the pivotarm 168 and a corresponding pivot aperture 194 on the distal portion 164of the anchor blade 14. The pivot arm 168 rotates in a plane parallel tothe width of the anchor blade 14 such that the pivot foot 174 can beseparated from the static foot 172 to permit passage of the screw shank,allowing the anchor blade to be disengaged from the bone anchor 15 aftertulip coupling. A lateral recess 194 is formed in the pivot foot 174 andis configured to receive a stabilization flange 196 therein. Thestabilization flange 196 extends away from the static foot 172 into thelateral recess 194 to ensure the pivot foot 174 remains in the desiredplane of motion.

The anchor blade 14 further includes an enclosed channel 198 positionedon one side of the anchor blade 14 and extending the length of theblade. A locking shaft 200 extends through the enclosed channel 198 andengages the pivot arm 168 to maintain the pivot foot 174 (and captureelement) in a closed position. This engagement is controlled by anactuator, for example a setscrew 202, that is engaged by a user toactuate the locking shaft 200. The setscrew 202 includes a threaded body204, a distal shelf 206, and a tool recess 208. The threaded body 204 isgenerally cylindrical and configured to engage a threaded recess 210 onthe proximal end 166 of the anchor blade 14. The distal shelf 206interacts with a proximal tab 212 on the locking shaft 200 in such a waythat when the setscrew 202 is rotated, accordingly the distal shelf 206exerts a downward force on the proximal tab 212, causing the lockingshaft 200 to advance distally through the enclosed channel 198 andengage the pivot arm 168. A capture ring 214 is provided to prevent thesetscrew 202 from backing out of the threaded recess 210. The toolrecess 208 is configured to receive a distal end 216 of a retractor 218that is used to actuate the setscrew 202. Although described herein as asetscrew 202, the actuator may be any element that a user may use tocause movement of the locking shaft 200, including but not limited to acam mechanism and the like. The anchor blade 14 further includes a track220 that slidably receives various instruments (e.g. shank/bladeinserter, tulip inserter) and light cables.

The coupler 158 is integrally formed with the proximal portion 166 ofthe anchor blade 14 and provides a spring-loaded quick connect andrelease mechanism for engagement with the central post 66 of the leftarm 28 (and/or the central post 98 of the right arm 30) described above.It should be understood that the anchor blades 14 and 16 areinterchangeable in that either anchor blade 14 or anchor blade 16 may beused with either the left arm 28 or right arm 30. Therefore, only theinteraction between the anchor blade 14 and the left arm 28 is describedin detail herein, however all features herein described also apply tothe interaction between the anchor blade 16 and the right arm 30. Thecoupler 158 has a proximal half 222 and a distal half 224. For thepurpose of this disclosure, the proximal half 222 is defined as theportion of the coupler 158 that engages with left retractor arm 28, andthe distal half 224 is defined as the portion of the coupler 158 thatengages with the secondary retractor 18 (or the right retractor arm, ifattached thereto). The proximal half 222 and distal half 224 of thecoupler 158 are identical and as such the various features common toboth halves will be assigned the same reference numerals for clarity.

The coupler 158 includes a housing 226 and a pair of buttons 228. Thehousing 226 includes a proximal face 230 on the proximal end 222 (and anidentical distal face on the distal end 224), an attachment aperture 232extending through the proximal face 230, a pair of button apertures 234,and an interior lumen 235. The proximal face 230 includes a pair offlanges 236 extending proximally from the proximal face 230. When theanchor blade 14 is mated to the left arm 28, the proximal face 230flushly interfaces with the distal face 64 of the left arm, and theflanges 236 engage with the recesses 68 formed in the distal face 64 ofthe left arm 28 to operated as a clutch, as described above. Theattachment aperture 232 receives the central post 66 of the left arm 28therethrough such that the central post 66 can extend into the interiorlumen 235 of the housing 226. The button apertures 234 are configured toallow passage of the buttons 228 into the interior lumen 235. Thebuttons 228 each have a top surface 238, a through-hole 240, a lowerridge 242, and a bottom post 244. The top surface 238 is generallyrounded to maintain a low profile and cause minimal disruption tosurrounding anatomy during use, and is provided as a user engagementsurface. The through-hole 240 receives the central post 66 therethrough.The lower ridge 242 is configured to nest within the circumferentialrecess 72 of the central post 66 to prevent egress of the central post66 during use. The bottom post 244 centers a spring 246 which biases thelower ridge 242 into the circumferential recess 72. During coupling ofthe anchor blade 14 and the left arm 28, the tapered leading end 70 ofthe central post 66 enables the central post 66 to overcome the bias andadvance until the lower ridge 242 is aligned with the circumferentialrecess 72, at which point the spring 246 causes the lower ridge 242 tosnap into circumferential recess 72. To release the blade 14, the userpresses downward on the top surface 238, which forces the lower ridge242 out of the circumferential recess 72, enabling removal of thecentral post 60. The buttons 228 are secured to the coupler 158 via pins245 that nest in recesses 247 on the buttons 228. The coupler 158 mayalso include alignment markings 248 that act in concert with alignmentmarkings on the arms 28, 30 to provide visual feedback to a user thatsufficient distraction is achieved.

The anchor blades 14, 16 transmit torque efficiently to the bone anchor15 (e.g. for compression/distraction) without any loss of polyaxial(tulip) motion. The anchor blade 14, 16 are reusable. The pivot foot 168of the anchor blade 14 allows for top down loading of large screws wherethe shank thread diameter is larger than the diameter of the shank head.The pivot foot 168 will allow a polyaxial tulip to be loaded in top downapproach without entrapping the anchoring point of the anchor blades.

FIGS. 18-19 illustrate an example of a secondary retractor 18 accordingto one embodiment. With additional reference to FIGS. 4 and 17, thesecondary retractor 18 can attach to an assembled retractor 10 and has aself-locking mechanism. The secondary retractor 18 is attachable to thecoupler 158 of the anchor blade 14 and comprises a retraction assembly250 and a blade assembly 252. The secondary retractor 18 allows forfurther connection to a secondary (e.g. medial) blade 20 and drivesfurther access to the spine medially with many degrees of freedom. Forexample, the secondary retractor 18 may provide for medial retraction,medial splay, caudal-cranial pivoting and caudal-cranial translation.The retraction assembly 250 provides medial retraction and comprises ahousing 254, a threaded shaft 256, and a perpendicular gear comprisingan actuating gear 258 and a translation gear 260, rendering fineresolution. The housing 254 has an interior lumen 262 through which thethreaded shaft 256 extends and within which the perpendicular gear iscontained. The actuating gear 258 includes a tooth portion 264 and anengagement recess 266. The engagement recess 266 extends through anaperture 268 formed in the housing 254 and provides an engagementelement for an actuator tool. The housing 254 has a circumferentialrecess 269 configured to accept a snap ring 270. The actuating gear 258is secured to the housing 254 via the snap ring 270 and a groovedretention washer 272. The translation gear 260 is orientedperpendicularly relative to the actuating gear 258. The translation gear260 includes a tooth portion 274, a post 276, and a threaded interiorlumen 278. The tooth portion 274 engages the tooth portion 264 of theactuating gear 258 and causes rotation of the translation gear 260 whenthe actuating gear 258 is rotated. The post 276 fits within a retainingring 280, which has a circumferential recess 282 configured to receive asnap ring 284 therein. Snap ring 284 also fits within groove 286 formedwithin the interior lumen 254 to secure the translation gear 260 to thehousing 254. A ball bearing race 287 is provided to prevent gallingbetween the gears during use.

The threaded shaft 256 mates with the threaded lumen 278 of thetranslation gear 260. As the translation gear 260 rotates, the threadedshaft 256 is caused to translate in either a medial or lateraldirection, depending on the direction of the rotation. The threadedshaft 256 further includes a proximal end 288 that is virtuallyidentical in structure and function to the distal face 96 of the firstarm 28 described above. To wit, the proximal end 288 includes a proximalface 290, a central post 292 protruding distally from the center of theproximal face 290 and a pair of opposing recesses 294 positioned on theperimeter of the proximal face 290 on either side of the central post292. The central post 292 is configured to mate with the attachmentaperture 232 of the anchor blade 14 (or anchor blade 16) to securelyattach the anchor blade 14 to the left arm 28. The central post 292 isgenerally cylindrical and includes a tapered leading end 296 and acircumferential recess 298 positioned between the leading end 296 andthe proximal face 290. These features interact with the quick releasemechanism of the anchor blade 14 described above in a manner that isidentical to the manner in which the corresponding structure of the leftretractor arm 28 interacts with the quick release mechanism of theanchor blade 14, and thus a repeat discussion is unnecessary. It shouldbe noted, however that in the example disclosed above in which theanchor blade 14 is attached to the left retractor arm 28 via theproximal end 222 of the coupler 158, the secondary retractor 18 may becontemporaneously attached to the distal end 224 of the coupler 158.

The blade assembly 252 extends generally perpendicularly from theretraction assembly 250 and includes a quick release housing 300 and asplay unit 302. The quick release housing 300 includes an attachmentaperture 304 for receiving the attachment post 358 of the secondaryblade 20 and a button 306 that is biased with a spring 308. The quickrelease housing 300 is identical to form and function to the samefeature described above in relation to the coupler 158, and thus adetailed description of the like features need not be repeated.Similarly, the splay unit 302 is identical in form and function to thesplay unit 74 of the left arm 28, and thus a detailed description of thelike features need not be repeated. It should be noted however that thesplay unit 302 allows for continuously variable blade splay and willactuate for example to allow for up to 40° of angular splay.

FIGS. 20-21 illustrate an example of a secondary retractor 310 accordingto another example embodiment. The secondary retractor 310 differs fromthe secondary retractor 18 described above in that secondary retractor310 attaches to both the left retractor arm 28 (via anchor blade 14) andthe right retractor arm 30 (via anchor blade 16). The secondaryretractor 310 is attachable to the coupler 158 of the anchor blade 14and a corresponding coupler 158′ of the anchor blade 16 (FIG. 33). Thesecondary retractor 310 comprises a retraction assembly 312, a bladeassembly 314, and a second attachment unit 316. The secondary retractor310 allows for further connection to a secondary (e.g. medial) blade 20and drives further access to the spine medially with many degrees offreedom. For example, the secondary retractor 310 may provide for medialretraction, medial splay, caudal-cranial pivoting and caudal-cranialtranslation. The retraction assembly 312 is identical to the retractionassembly 250 described above and thus any feature disclosed in relationto retraction assembly 250 is applicable to the retraction assembly 312,rendering a repeat discussion unnecessary. A crossbar 318 extendsgenerally perpendicularly from the retraction assembly 312 terminates atthe second attachment unit 316. The blade assembly 314 is positioned onthe crossbar 318 between the retraction assembly 312 and the secondattachment unit 316. The blade assembly 314 includes a quick releasehousing 320 and a splay unit 322. The quick release housing 320 includesan attachment aperture 324 for receiving the attachment post 358 of thesecondary blade 20 and a button 326 that is biased with a spring 328.The quick release housing 320 is identical in form and function to thesame feature described above in relation to the coupler 158, and thus adetailed description of the like features need not be repeated.Similarly, the splay unit 322 is identical in form and function to thesplay unit 74 of the left arm 28, including a captured jackscrew 330 anda cap 332 and thus a detailed description of the like features need notbe repeated. It should be noted however that the splay unit 322 causespivoting of the quick release housing 320 (and thus the secondary blade20) but does not cause rotation of the crossbar 318 or the secondattachment unit 316. The splay unit 322 allows for continuously variableblade splay and will actuate for example to allow for up to 40° ofangular splay.

The second attachment unit 316 includes a base 334, an extension 336,and an attachment post 338. The attachment post 338 is generallycylindrical and includes a tapered leading end 340 and a circumferentialrecess 342 positioned between the leading end 340 and the extension 336.These features interact with the quick release mechanism of the anchorblade 16 described above in a manner that is identical to the manner inwhich the corresponding structure of the left retractor arm 28 interactswith the quick release mechanism of the anchor blade 14, and thus arepeat discussion is unnecessary.

FIGS. 22-26 illustrate a secondary retractor blade (e.g. medial blade)20 in greater detail. The secondary retractor blade 20 includes proximaltrack portion 344 and a distal blade portion 346. The proximal trackportion 344 has an inner face 348 and an outer face 350. The inner face348 includes a recess 352 for nesting with at least a portion of thedistal blade portion 346. The track portion 344 further includes a track354 for receiving a light cable (for example) and a plurality of ratchetapertures 356 positioned along the track portion 344 proximally of therecess 352. The outer face 350 includes an attachment post 358 extendinggenerally perpendicularly away from the outer face 350. The attachmentpost 358 is identical in form and function to the central post 66 of theleft retractor arm 28, and interacts with the quick release mechanism320 of the secondary retractor 310 in the same manner that the centralpost 66 of the left retractor arm 28 interacts with the quick releasemechanism of the coupler 158. The distal blade portion 346 includes ablade 360 and a guide flange 362. The blade 360 includes an inner face364, an outer face 366, and a serrated foot 368 at the distal tip. Theinner face 364 may include a slightly concave surface. The serrated foot368 curves toward the outer surface 366 and helps minimize tissue creepeffect. The guide flange 362 engages with the track 354 to couple thedistal blade portion 346 to the proximal track portion 344. The guideflange further includes a cantilever ratcheting mechanism 370 having aproximal end 372 that interacts with the apertures 356 to maintain adesired length of the blade construct. Guide pins 374 extend through pinapertures 375 in the distal blade portion 346 and into guide tracks 376to ensure the distal blade portion 346 maintains proper alignment duringuse.

FIGS. 23-26 illustrate the coupling of the secondary blade 20 to a bladeinserter 378. The blade inserter 378 includes a proximal handle 380 anda distal tip 382 separated by an elongated shaft 384. The proximalhandle 380 includes a release button 386 extending proximally therefrom.The distal tip 382 includes a side edges 384 that mate with the track354 on the proximal track portion 344 to couple the secondary blade 20to the blade inserter 378. The distal tip 382 further includes acantilever ratcheting mechanism 386 having a distal end 388 thatinteracts with the apertures 356 to maintain a secure hold on thesecondary blade 20.

To use the secondary blade 20, first the blade 20 is coupled to theinserter 378 as described above. It should be noted that the distalblade portion 346 should be initially placed in a fully extendedposition (i.e. positioned such that the distal end 372 of the cantileverratchet mechanism 370 engages the distal-most ratchet aperture 356 onthe proximal track portion 344. The secondary blade 20 is then manuallyadvanced into the surgical target site by the user. The distal tip ofthe blade 20 may be placed first with haptic feedback in the desiredlocation and then subsequently compressed and connected to the secondaryretractor 18. Optionally, the user may use the secondary blade 20 like aCobb instrument to elevate the tissue at the distal tip. Bladecompression (or lengthening if necessary) is achieved as follows: oncethe blade engages with an anatomical structure (e.g. soft tissue, bone),the distal end will stop moving. If the user continues to apply adownward force on the insertion instrument, the cantilever ratchetingmechanism 386 will cause the distal end 388 to vacate one ratchetaperture 356 for the next proximal ratchet aperture 356 and so on, untilthe desired blade compression is achieved. The user than maneuvers thesecondary blade 20 so that it connects to the secondary retractor 18 viathe features described above. If desired, the user may affect bladesplay while the inserter is still attached, or after it has beendisengaged. Further blade compression may occur during blade splay. Oncethe secondary blade has been inserted, the release button 386 may beused which causes the cantilever ratcheting mechanism 386 to re-engagethe ratchet apertures 356 while providing downward force to the distalblade 346, enabling the inserter 378 to be removed from the surgicalwound while contemporaneously allowing the secondary blade 20 tomaintain an extended state. By way of example, the distal blade portion346 of the secondary blade 20 may be made of a titanium materialselection that provides for intraoperative fluoroscopy radiolucency.

FIGS. 27-38 illustrate an example method of using the retractor 10 ofthe present disclosure in a TLIF procedure. A beneficial feature of theretractor assembly 10 described herein is that the bone anchor 15 may becoupled to the anchor blades 14, 16 prior to introduction into thesurgical target site. This is done by first unlocking the pivot foot168, inserting the neck 178 of the bone anchor 15 into the centeraperture 176, and then relocking the pivot foot 168 as described above(FIGS. 12-13). The bone anchor 15 is now coupled to the anchor blade 14,and now may also be coupled to a driver instrument 400 (FIG. 27) priorto advancement through the operative corridor. Once the patient has beenproperly positioned, the target area has been identified and exposurehas been established, the bone anchors 15 may be placed in the firsttarget sites. After tapping the target pedicles, the coupled bone anchor15, anchor blade 14, and inserter 400 may be advanced over the K-wire tothe target site. The anchor 15 is driven into the bone until either thedistal end of the driver 400 or the anchor blade 14 bottoms out on bone(FIG. 28). The K-wire may be removed after the threaded shank 182 entersthe posterior part of the vertebral body 5. These steps may be repeatedto place a second anchor blade 16 coupled with a bone anchor 15 in apedicle of an adjacent vertebral body 7 (FIG. 29).

At this point the access retractor body 12 can be attached to the anchorblades 14, 16 on either side (e.g. medial or lateral), however it can beadvantageous to attach the access retractor body 12 to the lateral sideof the anchor blades (i.e. away from the patient's spine) so to increasevisibility of the target area under fluoroscopy (FIG. 30). As describedabove, the access retractor body 12 is connected to the anchor blades14, 16 by inserting the central posts 66, 98 (FIG. 4) into thequick-connect couplers 158 of the anchor blades 14, 16. An audible clickwill sound when the access retractor body 12 is properly engaged to theblades. At this point the retractor assembly 10 may be attached to aarticulating arm (for example) using the articulating arm attachment 52.Positioning the retractor assembly 10 so that the anchor blades 14, 16are parallel to the disc space ensures the proper medial exposuretrajectory is achieved.

If distraction is desired, the anchor blade 14 may be splayed by using aT-handle (for example) to actuate the cap 80 of the splay unit 74 on theleft retractor arm 28 as described above. Similarly, the anchor blade 16may be independently splayed using a T-handle (for example) to actuatethe cap 112 of the splay unit 106 of the right retractor arm 30.Rotation of the T-handles in a clockwise direction causes the blades 14,16 to splay outward. Since the blades are coupled to the pedicle bonesvia the bone anchors 15, this will also cause distraction of the discspace. The coupler 158 may include alignment markings 248 that act inconcert with alignment markings 249 on the arms 28, 30 to provide visualfeedback to a user that sufficient distraction is achieved (FIG. 31).Once proper alignment has been achieved, the user may rotate the thumbtab 38 (or for example a T-handle, if desired) in a clockwise directionto open the retractor and provide soft tissue retraction and initialvisualization of the working corridor 22.

Once adequate soft tissue retraction as been achieved, asingle-engagement secondary retractor 18 (FIG. 32) or a dual-engagementsecondary retractor 310 (FIG. 33) may be added to enable medialretraction. The single-engagement secondary retractor 18 is attached byinserting the central post 292 into the distal half 224 of the coupler158 of the anchor blade 14. An audible click will sound when thesecondary retractor 18 has been properly engaged to the anchor blade 14.The dual-engagement secondary retractor 18 is attached by inserting thecentral post 292 into the distal half 224 of the coupler 158 of theanchor blade 14, and by inserting the attachment post 338 of the secondattachment unit 316 into the distal half 224′ of the coupler 158′ of theanchor blade 16. Audible clicks will sound when the secondary retractor310 has been properly engaged to each of the anchor blades 14, 16. Asecondary blade 20 is then selected and attached to an inserter 378, andthen attached to the secondary retractor 18 as described above withreference to FIGS. 23-26. Once the adequate medial blade retraction andsplay has been achieved the release button 386 is pressed on theinserter 378 to release the secondary blade 20 from the inserter 378.

FIGS. 35-38 illustrate the final positioning of the retractor assembly10 relative to the surgical target site. In particular, FIG. 38illustrates the retractor assembly in use with the secondary blade 20 ina retracted position. From this point the additional steps of the TLIFprocedure is carried out at this level including facetectomy,decompression, further distraction (optionally), disc and endplatepreparation, and interbody implant insertion. In preparation for rodinsertion, a tulip head (not shown) is attached to the bone anchor headwhile the anchor blades 15, 16 are engaged with the bone anchor 15 ateach vertebral level. The rods may also be placed and locked down whilethe anchor blades 15, 16 are attached. Once the rod construct issufficiently in place, the pivot foot 168 is unlocked by rotating thesetscrew 202 counterclockwise, which causes the locking shaft 200 toretreat proximally through the enclosed channel 198 and thus disengagethe pivot arm 168 (FIGS. 11-15). The pivot arm 168 is allowed to movefreely, enabling the anchor blade 14 to be dissociated from the boneanchor 15 and removed from the working channel 22. The second anchorblade 16 may be removed from the working channel 22 in the same manneras the anchor blade 14, and the operative wound is closed, completingthe procedure.

For multi-level TLIF procedures, the retractor assembly 10 may be usedin a “marching technique” to reduce the number of times the pedicleshave to be targeted. For example, for a two-level TLIF (involving threeadjacent vertebrae), coupled anchor-blade-inserters are placed in eachtarget pedicle (i.e. three blades in total at two adjacent levels). Theprocedure is performed as described above with relation to one of thelevels while the third anchor blade is unattached to anything (exceptthe implanted bone anchor). After the TLIF is completed at the firstlevel, the retractor assembly 10 is removed except for the anchorblades. The first anchor blade is left attached to the bone anchor. Themiddle blade is rotated 180° and then reconnected to the accessretractor body (the other retractor arm), along with the third anchorblade. The TLIF is performed at the second level. Once the tulips aredown the rod can be placed connecting all 3 levels and the procedure canthen be finished.

FIGS. 39-41 illustrate an example of an alternative anchor blade 414configured for use with the tissue retractor assembly 10 describedherein. Generally, anchor blade 414 has a blade portion 418 extendingfrom a coupler 420. The blade portion 418 is identical in form andfunction to the blade portion 156 of the anchor blade 14 describedabove, and therefore all features disclosed with respect to bladeportion 156 are attributable to blade portion 418 as well, rendering arepeat disclosure unnecessary.

The coupler 420 is integrally formed with the proximal portion of theanchor blade 414 and provides an alternative spring-loaded quick connectand release mechanism for engagement with the central post 66 of theleft arm 28 (and/or the central post 98 of the right arm 30) describedabove. It should be understood that the anchor blades 414 and 416 areinterchangeable in that either anchor blade 414 or anchor blade 416 maybe used with either the left arm 28 or right arm 30. Therefore, only theinteraction between the anchor blade 414 and the left arm 428 isdescribed in detail herein, however all features herein described alsoapply to the interaction between the anchor blade 416 and the right arm430. The coupler 420 has a proximal half 422 and a distal half 424. Forthe purpose of this disclosure, the proximal half 422 is defined as theportion of the coupler 420 that engages with left retractor arm 28, andthe distal half 424 is defined as the portion of the coupler 420 thatengages with the secondary retractor 18 (or the right retractor arm 30,if attached thereto). The proximal half 422 and distal half 424 of thecoupler 420 are identical and as such the various features common toboth halves will be assigned the same reference numerals for clarity.

The coupler 420 includes a housing 426 and a pair of release buttons428. The housing 426 includes a proximal face 430 on the proximal end422 (and an identical distal face on the distal end 424), an attachmentaperture 432 extending through the proximal face 430, a trigger aperture433 extending through the proximal face 430 below the attachmentaperture 432, a pair of button recesses 434, and an interior lumen 435.The proximal face 430 includes a pair of flanges 436 extendingproximally from the proximal face 430. When the anchor blade 414 ismated to the left arm 28, the proximal face 430 flushly interfaces withthe distal face 64 of the left arm, and the flanges 436 engage with therecesses 68 formed in the distal face 64 of the left arm 28 to enablepivoting of the anchor blade 414 relative to the left arm (e.g. bymoving the retractor body) until a sidewall of flange 436 engages asidewall of the recess 68, after which the blade will rotate with thearm in response to user activation of the splay unit 74. The attachmentaperture 432 receives the central post 66 of the left arm 28therethrough such that the central post 66 can extend into the interiorlumen 435 of the housing 426. The button recesses 434 are configured toprovide a low profile nesting location for the release buttons 428 whenthe anchor blade 414 is in a “ready” state (e.g. prior to coupling witha left arm 28). The button recesses 434 each have a spring recess 438positioned therein for housing one end of the button springs 440. Therelease buttons 428 each have a top surface 442, a bottom surface 444,and a locking flange 446 extending from the bottom surface 442. The topsurface 442 is generally rounded to maintain a low profile and causeminimal disruption to surrounding anatomy during use, and is provided asa user engagement surface. The bottom surface 444 includes a springrecess 448 for housing the other end of the button spring 440. Thelocking flange 446 extends from the bottom surface 444 and includes athrough-hole 450 and a trigger slot 452 extending below the through-hole450. The through-hole 450 receives the central post 66 therethrough. Therim 454 of the through-hole 450 is sized and configured to nest withinthe circumferential recess 72 of the central post 66 to prevent egressof the central post 66 after the central post 66 has been fully insertedinto the lumen 435 (thereby locking the anchor blade 414 to the left arm28). The trigger slot 452 is divided into a first part 456 and a secondpart 458. The first part 456 has a width dimension that is complementaryto the diameter of the middle portion 468 of the trigger button 460. Thesecond part 458 has a width dimension that is complementary to thediameter of the end portion 470 of the trigger button 460. The couplerfurther includes a spring-loaded trigger button 460 that is at leastpartially housed, along with a trigger spring 462, within a triggerlumen 464 positioned underneath the interior lumen 435. The triggerbutton has a base 466, a middle portion 468 having a diameter that issmaller than the diameter of the base 466, an end portion 470 having adiameter that is smaller than the diameter of the middle portion 468,and an end cap 472 having a diameter that is greater than the diameterof the end portion 470.

In a detached or “ready” state (e.g. prior to coupling with the left arm28), the trigger spring 464 exerts an outward force on the base 466 ofthe trigger button 460, which biases the middle portion 468 of thetrigger button 460 through the trigger aperture 433 and at leastpartially into the first part 456 (i.e. wider part) of the trigger slot452. This pulls the release button 428 downward so that the releasebutton 428 is nested within the button recess 434 and the button springs440 are compressed. In this state, the attachment aperture 432 of thehousing 422 is aligned with the through-hole 450 of the release button428, thereby allowing the insertion of the central post 66 into theinterior lumen 435 to enable coupling of the anchor blade 414 and theleft arm 28. During coupling of the anchor blade 414 and left arm 28, asthe central post 66 is advanced through the through-hole 450 andattachment aperture 432 and into the interior lumen 435. As thisadvancement is occurring, the distal face 64 of the left arm encountersthe trigger button 460 and exerts an inward force on the end cap 472.This inward force is greater than the outward force exerted by thetrigger spring 462, and the trigger button 460 is urged into the triggerlumen 464. As the trigger button 460 is pushed further into the triggerlumen 464, the middle portion 468 is pushed entirely out of the firstpart 456 of the trigger slot 452, leaving only the end portion 470 inthe trigger slot. The button spring 440 is thus allowed to releaseenergy by exerting an upward force on the bottom surface 444 of therelease button 428. This force snaps the release button 428 up, causingthe end portion 470 of the trigger button 460 to snap into the secondpart 458 of the trigger slot 452 while simultaneously causing the rim454 of the through-hole 450 to snap into the circumferential recess 72of the central post 66 to prevent egress of the central post 66 afterthe central post 66 has been fully inserted into the lumen 435 (therebylocking the anchor blade 414 to the left arm 28). The forcible movementof the release button 428 makes the metal-on-metal contact between therim 454 and the circumferential recess 72 audible, providing feedback tothe user in the form of an audible “click” to indicate that the anchorblade 414 is secured to the retractor arm. In this “locked” state, theattachment aperture 432 and through-hole 450 are no longer in alignment(e.g. FIG. 39). To release the anchor blade 414, the user pushes therelease button 428. This brings the attachment aperture 432 andthrough-hole 450 back into alignment while simultaneously evicting therim 454 from the circumferential recess 72, enabling the central post 66to be removed from the coupler 420.

FIG. 42 illustrates the tissue retractor assembly 10 in use with anchorblades 414, 416 attached thereto. As with the anchor blades, 14, 16described above, the anchor blades 414, 416 are virtually identical inform and function and therefore all features disclosed herein withregard to anchor blade 414 may be attributable to anchor blade 416 aswell.

FIGS. 43-45 illustrate another example of an alternative secondaryretractor 480 that can attach to an assembled retractor 10 and has aself-locking mechanism. The secondary retractor 480 is attachable to thecoupler 158 of the anchor blade 14 (or coupler 158′ of anchor blade 16,or coupler 420 of anchor blade 414, etc.) and comprises a retractionassembly 482 and a blade assembly 484. The secondary retractor 480allows for further connection to a secondary (e.g. medial) blade 20 anddrives further access to the spine medially with many degrees offreedom. For example, the secondary retractor 480 may provide for medialretraction, medial splay, caudal-cranial pivoting and caudal-cranialtranslation. The retraction assembly 482 provides medial retraction andcomprises a housing 486, a rack 488, a gear 490, and a pawl 492. Thehousing 486 has an interior lumen 494 through which the rack 488extends, a gear recess 496 that receives the gear 490, and a pawl recess498 that provides a low profile nest for the pawl 492. The rack 488includes a proximal attachment end 500, a set of top teeth 502, and aset of side teeth 504. The attachment end 500 is virtually identical instructure and function to the distal face 96 of the first arm 28described above, and thus a repeat discussion is unnecessary. The topteeth 502 are spaced relatively close together and are configured toengage with the pawl 492. The side teeth 504 are spaced farther apartthan the top teeth 502 and are configured to engage the gear 490. Thelarger side teeth 504 allow for greater mechanical advantage duringretraction when engaged with the gear 490, while the smaller teeth 502allow for more discreet locking positions. The gear 490 includes a toothportion 506 and an engagement recess 508. The engagement recess 508receives a post 510 of an actuator element 512, which also includes anengagement recess 514 for engaging an actuator tool (not shown).Rotating the actuator element 512 causes the gear 490 to rotate, whichin turn causes the rack 488 to translate within the lumen 494. The pawl492 includes a distal engagement tip 516 and a spring-loaded proximalrelease lever 518. The distal engagement tip 516 engages with the topteeth 502 on the rack 488 to finely control the locking positions. Aspring 520 biases the pawl 490 to contact the rack 488 in a ratchet-likemanner. Pushing on the release lever 518 causes the distal engagementtip 516 to lift off the rack 488, enabling free movement of the rack488. The blade assembly 484 is identical to the blade assembly 252described above with reference to secondary retractor 18, and thus anyfeature disclosed in relation to blade assembly 252 is applicable to theblade assembly 484, rendering a repeat discussion unnecessary.

FIGS. 46-48 illustrate another example of an alternative secondaryretractor 530 that can attach to an assembled retractor assembly 10according to one embodiment. The secondary retractor 530 is attachableto the caudal anchor blade 14 and comprises a retraction assembly 532and a blade assembly 534. The secondary retractor 530 allows for furtherconnection to a secondary (e.g. medial) blade 536 and drives furtheraccess to the spine medially with many degrees of freedom. For example,the secondary retractor 530 may provide for medial retraction, medialsplay, caudal-cranial pivoting and caudal-cranial translation. Theretraction assembly 532 provides medial retraction and comprises ahousing 538, a rack 540, and a gear 542. The housing 538 has an interiorchannel 544 through which the rack 540 extends and within which the gear542 engages the rack 538. The gear 542 includes a tooth portion (notshown) that engages the rack 540 and an engagement recess 546 thatprovides an engagement element for an actuator tool. The housing 538further has an attachment flange 548 extending generally downward fromthe housing 538, and a pawl 550 configured to engage the teeth 552 ofthe rack 540, enabling fine resolution. The attachment flange is sizedand configured to slideably engage the track 220 of the anchor blade 14(FIG. 11). The rack 540 is double sided and has a first set of teeth 552positioned on an opposite side of the rack from a second set of teeth554. The first set of teeth 552 are spaced relatively close together andare configured to engage with the pawl 550. The second set of teeth 554are spaced farther apart than the first set of teeth 552 and areconfigured to engage the gear 542. The larger second set of teeth 554allow for greater mechanical advantage during retraction when engagedwith the gear 542, while the smaller first set of teeth 552 allow formore discreet locking positions.

The blade assembly 534 includes a base 556, pivoting crossbar 558, ablade coupler 560 and a splay unit 562. The base is positioned at thedistal end of the rack 540 and includes a channel 564 for receiving thepivoting crossbar 558. The pivoting crossbar 558 can translate up to aninch in distance and can rotate on axis up to 40° in a continuouslyvariable fashion. The pivoting crossbar 558 may freely translate withinthe channel 564 and has an internal O-ring (not shown) which appliesfriction during translation guidance. The splay unit 562 controlsrotation and is identical in form and function to the splay unit 74 ofthe left arm 28, and thus a detailed description of the like featuresneed not be repeated. The pivoting crossbar 558 is attached to acrankshaft 565 that has an offset knuckle 566 and pivoting stud 568allowing for attachment of a secondary blade 536. The crankshaft 565allows the secondary blade 536 to be splayed offset of the axis ofrotation of the pivoting crossbar 558. The eccentric movement persuadesa secondary blade 536 to move up and out of the surgeon's line of sightwhile splaying. The secondary blade 536 attaches to the secondaryretractor 530 with an internal self-locking quick connect mechanism, forexample such as those described above.

FIG. 48 illustrates the secondary retractor 530 in use with a standardrack retractor 570, shown by way of example only. The secondaryretractor 530 may be used with the retractor assembly 10 described abovewithout departing from the scope of the disclosure. By way of exampleonly, the standard rack retractor 570 includes a first arm 572 andsecond arm 574 connected via a crossbar rack 576. The first and secondarms 572, 574 are virtually identical to the left and right arms 28, 30described above. The crossbar rack 576 is received within a housing 578,which itself has a gear 580 and pawl 582. Anchor blades 584, 586 differfrom the several embodiments described above in that they attach to thebone anchors 15 via hoop shims 588.

While the inventive features described herein have been described interms of a preferred embodiment for achieving the objectives, it will beappreciated by those skilled in the art that variations may beaccomplished in view of these teachings without deviating from thespirit or scope of the invention.

What is claimed is:
 1. A method for attaching a fixation system to thespine of a patient, the fixation system including at least two boneanchors and a spinal rod linking the at least two bone anchors,comprising the steps of: connecting a first bone anchor to a firstretractor blade, advancing the first bone anchor and first retractorblade together to a first spinal vertebra, and anchoring the first boneanchor through a pedicle of the first spinal vertebra; connecting asecond bone anchor to a second retractor blade, advancing the secondbone anchor and second retractor blade together to a second spinalvertebra, and anchoring the second bone anchor through a pedicle of thesecond vertebra, wherein the second vertebra is separated from the firstvertebra by an intervertebral disc space and the first vertebra, secondvertebra, and intervertebral disc space comprise a first spinal level;connecting the first retractor blade and the second retractor blade witha retractor body, the retractor body being positioned laterally awayfrom the spine relative to the first and second retractor blades,operating the retractor body to expand an operative corridor formedbetween the first retractor blade and second retractor blade from theskin level of the patient to the spine; and linking the first boneanchor and the second bone anchor with the spinal rod.
 2. The method ofclaim 1, comprising the additional step of adjusting an angle of theoperative corridor until the operative corridor is parallel to theintervertebral disc.
 3. The method of claim 2, wherein adjusting theangle of the operative corridor is accomplished by moving a proximal endof the first retractor blade and a proximal end of the second retractorblade in the same direction while a distal end of the first retractorblade remains positioned adjacent the first pedicle and a distal end ofthe second retractor blade remains positioned adjacent the secondpedicle.
 4. The method of claim 3, wherein the angle of the operativecorridor is adjusted in one of a cephalad or caudal direction.
 5. Themethod of claim 3, wherein the angle of the operative corridor isadjusted in one of an anterior and posterior direction.
 6. The method ofclaim 3, wherein the angle of the operative corridor is adjusted in bothone of a cephalad and caudal direction and in one of an anterior andposterior direction.
 7. The method of claim 3, wherein the firstretractor blade is connected to the first bone anchor in a polyaxialengagement and the second retractor blade is connected to the secondbone anchor in a polyaxial engagement.
 8. The method of claim 2,comprising the additional step of operating the retractor body todistract the intervertebral disc space.
 9. The method of claim 1,comprising the additional step of coupling a secondary retractor bodydirectly to one of the first retractor blade and second retractor blade,the secondary retractor body being positioned medially relative to thefirst and second retractor blades, and connecting a third retractorblade to the secondary retractor body.
 10. The method of claim 9,wherein the secondary retractor body includes a retraction mechanism andsplay mechanism.
 11. The method of claim 10, comprising the additionalstep of operating at least one of the secondary retractor bodyretraction mechanism and splay mechanism to expand the size of theoperative corridor medially.
 12. The method of claim 9, wherein thesecondary retractor body couples directly to the first retractor bladeand the second retractor blade.
 13. The method of claim 1, wherein aportion of the first bone anchor is connected to the first retractorblade via a capture ring integral to and extending from a distal end ofthe first retractor blade, the capture ring having a center aperturesized to receive a neck of a bone anchor therein.
 14. The method ofclaim 13, wherein the capture ring comprises a static foot and a pivotfoot, the pivot foot pivoting away from the static foot to an openposition to permit passage of the bone anchor neck into the capture ringand pivoting towards the static foot to a closed position to capture thebone anchor neck within the capture ring center aperture.
 15. The methodof claim 14, wherein the first retractor blade further comprises a lockto lock the pivot foot in the closed position.
 16. The method of claim15, wherein the distal end of the first retractor blade includes astatic arm and a pivot arm pivotally coupled to the static arm, thestatic foot extending from the static arm and the pivot foot extendingfrom the pivot foot.
 17. The method of claim 9, wherein connecting thethird retractor blade to the secondary retractor body includes advancingthe third retractor blade to the spine while coupled to an insertiontool, using a distal end of the third blade to first elevate tissue offof the spine and then connecting the third blade to the secondaryretractor body and releasing the insertion tool.
 18. The method of claim17, comprising the additional step of applying downward pressure to afloating blade extension of the third retractor blade as the thirdretractor blade is retracted medially to facilitate clearing of thetissue from the facet, lamina, and base of the spinous process.
 19. Themethod of claim 1, comprising the additional step of operating on thefirst spinal level through the operating corridor prior to linking thefirst bone anchor and the second bone anchor with the spinal rod. 20.The method of claim 19, wherein operating on the first spinal levelincludes one or more of a facetectomy, decompression, annulotomy, anddiscectomy.
 21. The method of claim 20, wherein at least a discectomy isperformed and comprising the additional step of inserting an implantinto the intervertebral space after the discectomy.